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COPYRIGHT DEPOSIT. 



LABORATORY DIRECTIONS 

IN 

GENERAL BIOLOGY 

Prepared to accompany Text Book on General Biology 



By P, Wr CLAASSEN, Ph.D. 

ASSISTANT PROFESSOR OF BIOLOGY IN CORNELL UNIVERSITY 



ITHACA, N. Y. 

THE COMSTOCK PUBLISHING CO. 

1922 



.05 



COPYRIGHT 1922 
THE COMSTOCK PUBLISHING CO. 



NOV 27 "22 

©C1A692069 



PRESS OF W. F. HUMPHREY 
GENEVA, N. Y. 



PREFACE 

Although the following Laboratory Directions in General Biology 
have been prepared particularly to accompany Needham's text in 
General Biology, most of the exercises will be found adaptable for 
use with other texts. The majority of the studies included have 
been selected from Needham's text and have been modified or 
elaborated to suit the conditions for general class use. 

For a number of years it has been found desirable to supplement the 
outlines of the practical exercises in the text by printed or mimeo- 
graphed sheets until they have reached the present proportions. 
All of the exercises included have been used satisfactorily in both 
large and small classes in General Biology in Cornell University for 
a number of years. 

In order to save the student from spending much time in doing 
non-productive routine work, such as preparing tabulation sheets 
etc., a number of partially finished drawings, tabulation sheets etc., 
are included in the envelope in the back of the book. These may, or 
may not, be used as the instructor sees fit. In the back part of the 
manual are also included figures and brief descriptions of the genera 
of planet on organisms. For the beginning student these figures and 
descriptions will simplify the identification of the more common 
plancton organisms encountered. 

The writer is greatly indebted to Dr. J. G. Needham for his en- 
couragement in the preparation of this manual; and for his permission 
to incorporate material from his text book in General Biology; 
to Dr. O. A. Johannsen for the use of material from his ' 'Laboratory 
Directions in General Biology" which were prepared by him and 
used in the course in General Biology in Cornell University fora 
number of years; and to Dr. Johannsen and Dr. J. T. Lloyd for 
the use of the plates of plancton organisms, and to other colleagues; 
for helpful suggestions and criticisms. 

p. w. a 



CONTENTS 

Laboratory Directions in General Biology 7 

Exercise 1 — Use of Compound Microscope 9 

Exercise 2 — Study of Common Galls, etc 12 

Exercise 3 — Algae, The Simpler Plants 16 

Exercise 4 — Protozoa, The Simpler Animals 18 

Exercise 5 — Physiology of the Cell 22 

Exercise 6 — Flagellates, The Intermediate Organisms 25 

Exercisa 7 — Bacteria and Fungi 27 

Exercise 8 — Reproduction Among the Simpler Organisms 31 

Exercise 9 — Bryophytes (Liverworts and Mosses) 35 

Exercise 10 — Pteridophytes (Ferns) 39 

Exercise 11 — Coelenterates (Hydra) 43 

Exercise 12-13 — Annelida (Earthworm) 46 

Exercise 14 — Cellular Structure of the Earthworm 52 

Exercise 15 — Arthropoda (Grasshopper) : 54 

Exercise 16 — Vertebrates. The Embryology or Development of the Frog. . 57 

Exercise 17-18— Vertebrates. The Frog 60 

Exercise 19 — Histology of the Frog 67 

Exercise 20 — Homology 70 

Exercise 21 — Serial Homology. Plasticity of Form and Persistence of Type 

in Malacostraca 73 

Exercise 22 — Phylogeny 76 

Exercise 23 — Ontogeny 77 

Exercise 24 — Mitosis 79 

Exercise 25 — Relation Between Fecundity and Nuture 82 

Exercise 26 — External Metamorphosis of Insects 85 

Exercise 27 — Internal Metamorphsis in Insects 86 

Exercise 28 — Plancton 89 

Exercise 29 — Woodland Plant Society 91 

Exercise 30 — Pollen Production as Affected by Its Mode of Distribution ... 92 

Exercise 31 — Readaptation of Insects to Aquatic Life 94 

Exercise 32 — Animal Coloration 95 

Exercise 33 — Demonstration of the Functions of some of the Principal Parts 

of Nervous System of the Frog 96 

Exercise 34 — The Instincts of the Tent Caterpiller 98 

Exercise 35 — Learning by Trial and Error in Chicks 99 

Genera of Plancton Organisms 102 

Blue-Green Algae 103 

Green Algae 105 

Desmidiacae 107 

Diatoms 109 

Flagellata Ill 

Crustacea 113 

Rotifera 115 



LABORATORY DIRECTIONS IN GENERAL BIOLOGY 

1. Equipment. Each student will provide himself with the 
following : 

1. A copy of Needham's General Biology. 

2. A copy of Claassen's Laboratory Directions in General 
Biology. 

3. Six manila covers 8 x 10^ for laboratory reports. 

4. Two kinds of paper to fit the covers: (a) plain drawing 
paper and (b) ruled paper for notes. 

5. One drawing pencil 6H. 

6. A good rubber eraser. 

7. Six glass slides. 

8. One dozen y^ inch cover glasses No. 2, square or circular. 

9. One piece of absorbant cloth for cleaning slides and cover 
glasses. 

10. A set of dissecting instruments consisting of: scalpel, 
scissors, forceps, two dissecting needles, medicine dropper and 
a ruler graduated in millimeters. 

This equipment should always be brought to the laboratory. 

2. Laboratory Reports. Laboratory notes and drawings 
must be original. Copied work will not be accepted. Drawings 
are to be finished in the laboratory and left properly labeled and en- 
closed in manila covers at the place designated by the instructor. 
All papers handed in must bear the student's name, day and time of 
his section, and seat number. 

Drawings. Every line and spot in the drawing should represent 
some feature in the object, and no mark should be made which does 
not find its counterpart in the object. Outlines should be com- 
plete without loose ends, hazy joints or dim angles. Impressionist 
drawings, though perhaps artistic, have no scientific value. All 
parts should be labeled. 

Summary. The answers called for in the summary should be 
brief but to the point. The summary is to be handed in at the 
beginning of the following laboratory period. 

3. Grades, etc. The records for each section will be in the 
hands of the laboratory instructor. All questions concerning grades, 
excuses, and make-ups after excused absences, are to be taken up 
directly with him. Any further requirements as to note-books 

7 



8 

will be explained by the instructor in charge. Diligence, punctuality 
and sustained effort will be considered in making up the final grades. 
A student who fails to hand in reports, summaries, or lecture notes on 
time will not receive a passing grade at the end of the term. 
No credit will be given on: — 

a. Reports, lecture notes, and summaries that have been 
copied from the work of another. 

b. Reports, etc., another student has used as a copy. 

c. Reports, lecture notes and summaries that are late. 

d. Work done in sections other than the one to which the stu- 
dent has been assigned. 

e. Reports, etc., done in collaboration. 

4. Absences from Laboratory. A student unavoidably absent 
from the laboratory, upon presentation of a properly certified excuse 
from the Secretary of his College, will be given the opportunity to 
take a "make-up." "Make-ups" will only be given on certain 
Saturday afternoons. A list of these "make-up" periods will be 
found posted in the laboratory. Students wishing to attend the 
"make-up" section must deposit a slip of paper in the "make-up" 
box in the laboratory, stating the subject of the laboratory work 
which they have missed and which they wish to make up. These 
slips must be deposited in this box at least two days previous to 
the time of the "make-up." The "make-up" must be taken within 
three weeks after the absence is incurred, unless a further extension 
(in writing) is granted by the instructor in charge. 

5. Lecture Attendance. The names of the students with 
their seat numbers will be found posted at the door of the lecture 
room. Students are not permitted to change their assigned places 
without the consent of the instructor. The lecture notes, which 
must bear subject, number, and date, are to be handed in with the 
laboratory report at the following laboratory period. 



EXERCISE 1 
USE OF THE COMPOUND MICROSCOPE 

References. Needham, General Biology, pp. 513-519; Gage, The Micro- 
scope. 

Material and Apparatus Needed. Compound microscope, lens paper, 
glass slides and cover glasses, prepared slide marked "M", alcohol, ruler, paper 
and pencil. 

Caution. Do not handle the microscope until after the instructor has ex- 
plained its mechanism. The compound microscope is a very delicate instru- 
ment and should be treated with great care. Keep the lenses clean, wipe them 
only with lens paper which the instructor will provide. 



Coa 

Adjustment 



LABORATORY EXERCISE 

a. Record on your paper the mark or number with which the 
microscope is marked (i. e. B20 or B43, etc). 

b. Adjustments. Compare figure 1 
with your microscope and learn to recog- 
nize the different parts of the microscope. 
Learn something of the mechanism of the 
microscope. Slowly turn the milled head 
(wheel) at the side of the tube and note' 
the movement of the objective. This is 
known as the coarse adjustment. Never 
move the tube down until it touches the stage or 
goes through the opening in the stage. Next 
turn the milled head (wheel) at the head 
of the pillar (in some microscopes located 
{ ^^====£^=2==^^ at the side) and note that while there is a 

| Base ^^J 

LJ ~"^ similar movement as with the coarse ad- 

Fig, i justment, the motion is much slower. 

This is known as the fine adjustment. Hence the approximate 
focusing should be done with the coarse adjustment, and final 
focusing with the fine adjustment. Determine both limits for each 
adjustment, i. e., the approximate number of millimeters up and 
down which each adjustment will move the objective. Record your 
results in your note book. 

Place a little talcum powder on a glass slide and examine under the 
low power of the microscope. (The instructor will explain the dif- 

9 




CONDENSER 
ubstage 



10 

f erence and use of low and high power magnification.) Note the size of 
the particles. Then turn the high power objective on the 
slide and examine again. Now place a few pollen grains 
on the slide in a drop of water, put on a cover glass, 
and examine under low and high power. What is the distance (in 
millimeters) between the lower surface of the lens and the top of the 
glass slide when an object is in focus (a) for low power, (b) for high 
power? With the low power objective clearly in focus, touch the 
front of the objective lightly with the moist finger, and observe how 
*the appearance of the objective is altered. The fingers are never 
optically clean. The slightest deposit on the surface of a lens dis- 
turbs its refractory harmony. Do not touch the glass of your lenses 
with the finger again, or with anything else, except on the occasions 
when if is necessary to clean them. Now clean your lenses with 
lens paper. Draw three or four of the pollen grains, each with a 
diameter of at least one inch. 

Examine also a hair, threads of cotton or wool and ocher objects 
which the instructor will provide. 

. d. Air entangled under the cover glass is a frequent source of 
trouble. The air may cling to the cover — will be likely to do so if 
the cover be dropped flat upon the object. Breathe upon one 
side of the cover to moisten it, and let it down with one edge in 
advance of the other. Learn to recognize air bubbles so as not to 
confuse them with structures. Mount a dry thread in a drop of 
water, cover . and examine with low power. Draw a portion of the 
thread as it appears under the microscope. Alcohol may be used 
'to remove the air. Remount the thread in a drop of alcohol; 
cover, allow a little time to soak, and observe the disappearance 
of the air. Then draw a portion of the thread again. 

e. Magnification of the Microscope. Determine the 
apparent diameter of the field by the method of double vision. 
Place the microscope in a vertical position, (never tilt it back- 
ward), then look through it with one eye, keeping the other eye 
fixed on a sheet of paper on the table below. Adjust the mirror so 
that there will be a clear image of the circular field apparently 
projected upon the paper. Now draw two parallel tangents to 
this circular image and measure the distance between. Next 
measure the distance from the eye to the table (suppose this to be 
12 inches.) Since the normal visual distance is 10 inches, the 
apparent diameter of the field will be 10/12 of the distance between 



11 

the parallel lines just drawn. Repeat for higher power. Note 
that the apparent diameter, being independent of the magnifica- 
tion of the object, is practically the same for both the high and 
low powers. 

f . Actual Diameter of the Field for Both Powers. Exam- 
ine the slide marked "M", under the compound microscope. Each 
mesh of the silk bolting cloth under the cover glass is just .0078 
inch from center to center of the thread. Count the meshes 
(heeding the fractional mesh if there be one) in a row through 
the center of the field. To determine the actual diameter of the 
field multiply this number of meshes by .0078. 

g. Determine the magnification for both low and high powers. 
Divide the apparent diameter of the field by the actual diameter 
to obtain the magnification. 

Summary 

1. What is the focal distance of a lens? 

2. What is the working distance? 

3. What is the effect of water between objective and cover glass? 

4. Why must a cover glass be used when examining wet objects under the 
compound microscope? 

5. Why do you use the low power for "finding" the object? 

6. What effect has an increase of magnification on size of field and working 
distance? 



EXERCISE 2 
A STUDY OF COMMON GALLS 

References. Needham, General Biology, pp. 35-47; Felt, E. P., Key to 
American Insect Galls; Thompson, M. T., An Illustrated Catalogue of Ameri- 
can Insect Galls, etc. 

Material and Apparatus Needed. Dissecting instruments, simple micro- 
scope, vegetable insect galls and tabulation sheets. 

A gall is an abnormal growth of plant tissue occasioned by a stimulus external 
to the plant itself. 

LABORATORY EXERCISE 

A number of galls and their inhabitants will be studied. Upon 
the sheet furnished, record the results of your observations on both 
gall and insect. The galls, properly labeled, will be found on the 
laboratory supply table. Begin with a large gall, such as the Round 
Gall of the goldenrod. Make a drawing of the gall twice natural 
size. With a knife or scalpel carefully cut open the gall until the larva 
in the central cavity is disclosed. Be careful not to cut directly 
through the center thereby destroying the insect inside. Examine 
the gall maker with the microscope and then record your observa- 
tions in tabulated form on the sheet provided. To determine what 
type of gall you have consult the information under the heading 
"Types of Galls" on page 13. 

In order to determine the name of the insect in the gall and the 
order and family to which it belongs examine the specimen care- 
fully under the microscope and identify it by means of the table or 
key found on page 13. 

Study as many different types of galls as the time will permit, 
following the directions given for the goldenrod. 

Before handing in your sheet study it carefully and copy the data 
which you will need in preparing the summary which is due next 
week. 

TYPES OF GALLS 1 

Galls are classified into types according to their structure. They 
may first be divided into two classes, open and closed galls, i. e., 

1 Examine examples of these types on demonstration table. 

12 



13 



■galls which either have a natural opening through which the insect 
may escape or else they are entirely closed up, so that if the insect 
wishes to escape it must cut an opening through the wall to the 
outside. The open and closed galls again may be subdivided ac- 
cording to the following table: 



Open 



Closed 



Felted 

Scroll 
Pocket 

Mantle < Fluted 

[ Covering 



Simple 



Compound 
Nucleated 



Caused by 
Mites 
Aphids 
Aphids 
Aphids 
Gall 
midges, etc 



Found on 
Boxelder, grape etc. 
Elm, etc. 
Witch hazel, etc. 
Elm, etc. 



Hawthorn, etc. 



Midges, Oak, willow, 

sawflies, goldenrod, 

moths, ragweed, hickory, 

wasps, etc. 

beetles 

Wasps Oak, etc. 

Wasps Oak, etc. 




Figure 2. Diagrams of Typical Forms of Galls. 



.A. open felted; B. open scroll; C. open fluted; D. open pocket; E. open cov- 
ering; F. closed simple; G. closed compound; H. closed nucleated. 



14 

KEY TO THE COMMONER INSECT LARVAE AND MITES 

FOUND IN GALLS 

Note. This table cannot be used for the pupae or adults. 

A. Body short and thick; legs rather long, small animals, found 
only in open galls. 

B. Head fused with body and not distinct; 2 or 4 pairs of legs; 
very small animals always gregarious and found in felted galls. 

Order — Acarina 
Family — Eriophiidae 
Common name — Mites 
BB. With a distinct head, three pairs of legs; small insects found 
in open galls. 

Order — Hemiptera 
Family — Aphididae 
Common name — Aphids or plant lice. 
AA. Body cylindric, worm-like, legs minute or none. 

B. With 3 pairs of minute legs under the thoracic segments; 
found singly in closed galls. 

C. With a brown shield covering the prothorax above, body 
covered with stiff bristles. 

Order — Lepidoptera 
Family — Several 
Common name — Moth larva 
CC. Prothorax not covered by a brown shield. 

D. With rudimentary legs (fleshy prolegs) underneath some 
of the abdominal segments. 

Order — Hymenoptera 
Family — Tenthredinidae 
Common name — Sawfly larva 

DD. With no prolegs underneath the abdomen. 

Order — Coleoptera 
Family — Several 
Common name — Beetle larva 
BB. Legless — Found in either open or closed galls, usually 
singly. 

C. With a distinct head segment; body arcuate (curved), color 
white. 

D. Body segments deeply wrinkled; head brown; skin dull 
white; singly in closed galls. 



15 

Order — Coleoptera 
Family — Curculionidae 
Common name — Weevil larva 
DD. Body segments smooth, shining, head mostly white; in 
closed galls. 

Order — Hymenoptera 

Family — Cynipidae 

Common name — Gall wasp larva 

CC. With the head segment greatly reduced, very minute, or 
wanting; in either open or closed galls. 

D. Under side of first segment behind the head with a. 
narrow blackish horny structure extending lengthwise with, 
the body; color of larva often red or yellow. , , 

Order — Diptera 
Family — Cecidomyidae 
Common name — Gall midge larva 
DD. Without the horny structure, color white. 

Other dipterous larvae. 

Summary 

1. Summarize the results of the preceding study in a table of the orders *of the 
gall makers prepared under the following column headings: 



Order Mouth-parts 


Habits 


Gall type 


of insects or mites 


biting or sucking 


solitary or 
gregarious 


. pocket,, 
nucleated etc. 



2. What relation is there (a) between the type of mouth-parts and type of 
gall, and (b) between the order of insect and type of gall. 

3. List ten plants on which galls are commonly found. 

4. What is the economic importance of galls? 

5. What other agents, besides insects and mites, produce galls? •• 



EXERCISE 3 

THALLOPHYTES 
ALGAE— THE SIMPLER PLANTS 

References. Needham, General Biology pp. 56-68; Ward and Whipple, 
Fresh Water Biology; Tilden, J. Minnesota Algae etc. 

Material and Apparatus Needed. Compound microscope, glass slides and 
cover glasses, forceps, pipette, and a variety of algae representing unicellular, 
unbranched filamentous and branched filamentous forms. This should include 
Pleurococcus, Diatoms, Desmids, Spirogyra, Cladophora and others. 

From an evolutionary point of view it would probably be best to begin the 
laboratory work with the unicellular or simplest algae and then take up the more 
highly developed forms; but in order to simplify the work for the beginning 
student it is best to start with a form such as Spirogyra where the structures are 
more easily seen and the depth of focus more readily appreciated. Having 
studied this form the student will not be likely to have much difficulty in seeing 
the structures in the simpler and more obscure forms. 

LABORATORY EXERCISE 

a. Spirogyra. This unbranched filamentous alga, called pond 
scum, occurs in fresh water ponds and streams. 

1. Upon a clean glass slide mount a few filaments of Spirogyra 
in a small drop of clean water. Cover with a clean cover glass. 
Care should be taken not to get too many filaments on the slide 
for then they may obstruct a clear view. Find a single filament 
under the low power of the microscope and note the general struc- 
ture. Note that the filament is unbranched and is made up of 
elongate cylindrical cells placed end to end. Now examine the 
specimen under the high power. Make a drawing of a single cell 
on a large scale. The drawing should be at least 3 or 4 inches long 
and proportionately wide. Remember that you see only in one 
plane and in order to make out the detailed structure it is necessary 
to focus carefully up and down with the fine adjustment so that 
the entire structure may be determined. In your drawing label 
cell wall, chloroplast, pyrenoids, nucleus, cytoplasmic strands and 
vacuole. 

2. Draw on a large scale (one half inch- wide) a portion of the 
spiral band showing the pyrenoids and other structures in detail. 

b. Pleurcoccus. This unicellular alga occurs very commonly 
von the bark of trees, especially on the north or shady side, on moist 

16 



17 

rocks, bricks etc. Into a small drop of water on a glass slide scrape a 
very small amount of the alga, cover with a cover glass, tap the top of 
the cover glass gently with a pencil to separate the masses of algae, 
and examine under the high power. Note that the globular cells 
have a definite, fairly thick wall, a large lobed chloroplast whose 
lobes suggest several chloroplasts, and a nucleus, which in fresh 
specimens is difficult to see. Draw a single cell on a large scale (one 
inch in diameter). Label: cell wall, chloroplast and (nucleus). 
These cells multiply rapidly by division, the daughter cells adhering 
to each other and forming colonies of two, three, and four or more 
cells. Draw one or two colonies • composed of several cells. 

c. Desmids and Diatoms. Examine also a Desmid (Closterium) 
or Diatom. These also are one-celled plants occurring very commonly 
in fresh water. Some species' of diatoms are also found in salt water. 
Draw and label cell wall, nucleus, chromatophore and other details 
which the instructor will point out. 

d. Cladophora. This is a branched filamentous alga and is 
very commonly found attached to rocks in the bottom of fresh water 
streams. The cells are remarkable in containing many nuclei. In 
addition to the nuclei, the Cladophora cells contains many chloro- 
plasts in the peripheral layer of cytoplasm, and numerous pyrenoids 
in the plastids. Place a small bit of the plant on a glass slide in a 
drop of water and cover with a cover glass. Examine under low 
power and draw a portion of the plant to illustrate the branching 
•structure. Examine under the high power and draw a single cell in 
detail and label: cell wall, nuclei, and chloroplasts. 

e. Examine and draw other forms of algae which the instructor 
will provide. 

Summary 

1. Define a plant cell. 

2. What are the main constituents of a plant cell? 

3. Define cytoplasm, protoplasm, chloroplast, nucleus. 

4. Draw a cross section of Spirogyra through the nuclear region and label all 
the parts. 



EXERCISE 4 
PROTOZOA, THE SIMPLER ANIMALS 

References. Needham, General Biology, pp. 68-82; Hegner, Introduction 
to Zoology; Hegner, College Zoology; Hertwig, Manual of Zoology; Parker and 
Haswell, Text-book of Zoology. 

Material and Apparatus Needed. Compound microscope, glass slides, 
cover glasses, pipette, methyl green, iodine, and cultures of Amoeba, Paramoecia 
and Vorticella. 

Protozoa are the simplest animals. More so than in the Algae, the Protozoa 
consist of single cells. If colonial, the colls are all potentially alike. There are 
no tissues or organs present in the Protozoa, the individual cell performing all 
the functions, such as ingestion, digestion, metabolism etc. 

LABORATORY EXERCISE 

a. Amoeba. This animal is selected as the first specimen for 
study because it represents one of the simplest forms of animal life. 
It is microscopic in size and is found both in fresh and salt water. 
It averages about one-onehundreth of an inch in diameter, but the 
size varies in different species. Specimens for study may be pro- 
cured by collecting such water plants as water milfoil, lily leaves, 
algae and various decaying organic materials from ponds and ditches, 
and placing them in jars of water and allowing them to stand in a 
warm room. In a week or two a brown scum will appear on the 
surface of the water and in this scum Amoeba will usually be found. 

1 . Mount a drop of the Amoeba culture on a glass slide and cover 
lightly with a cover glass. Find a specimen under low power. 
The Amoeba is not easy to find and it may require a little time to 
locate a specimen. It appears like a little drop of jelly spreading 
out on a flat surface, quite translucent in the central portion and 
very transparent around the border. 

2. Describe the general appearance of the Amoeba, the shape, 
color, or lack of color etc. Be brief and specific. 

3. Study the specimen under the high power and observe: 

a. Pseudopodia, the blunt projections which are slowly pushed 
out from the body wall or drawn into it. Do they change position 
or shape? 

b. Ectosarc, a transparent outer border so clear that it is liable 
to be overlooked. 

18 



19 

c. Endosarc, 'the granular material within the ectosarc com- 
prising the greater bulk of the animal. 

d. Nucleus, a rounded, highly refractive, somewhat grayish 
body within the endosarc. (If you do not see the nucleus clearly 
in your specimen, examine the demonstration specimen which has 
been stained.) 

e. Contractile Vacuole, a rounded clear spot within the body. 

f. Indigested Food Particles. These appear darker and are 
of various sizes, aggregated usually more or less into round food 
balls or vacuoles, which may be seen moving about in the endosarc. 
4. Make an enlarged drawing of the amoeba, not less than two 

inches in diameter, showing all the structures. Label: ectosarc, 
endosarc, nucleus, contractile vacuole and food vacuole. 

b. Paramoecium. Paramoecia can usually be found in the 
same localities as Amoebae. A hay infusion, (pond water to which 
some dead grass and leaves have been added) a week or more old 
will usually yield great numbers of specimens for study. The 
Paramoecia will be found in the scum on the surface of the water. 
They are much larger than Amoeba and may be seen as small white 
specks, just visible to the unaided eye. They measure about one 
fiftieth of an inch in length. Paramoecium, like Amoeba, consists of 
a single cell, but it is much more highly specialized and always tends 
to preserve a definite form. 

1. Mount a drop of the Paramoecium culture on a glass slide. 
Include a little trash from the jar. Do not put on a cover glass. 
Examine under low power and by carefully and slowly moving the 
slide about, follow some of the Paramoecia as they go swimming 
around. Observe the spiral course of swimming, and the resultant 
rapid motion directly forward. What relation does the oblique 
groove (oral groove) bear to the axis of the spiral course in which the 
animal swims? Describe clearly the details of this motion. 

2. Place a cover glass over a drop of water containing the Para- 
moecia, including some particles of trash to avoid crushing the speci- 
mens, and find a place where a Paramoecium is repeatedly meeting 
with obstructions to his swimming. Describe carefully the move- 
ments by which an obstruction is avoided. What relation does his 
turning aside bear to the position of the oral groove? 

3. Detailed Study of Structure of Paramoecium. Mount 
another drop containing Paramoecia, adding thereto a little 
methyl green or iodine. This kills and stains the animal and renders 



20 

its structure more readily visible. Cover lightly with a cover glass 
and study the details of structure. Draw on a large scale (5 inches in 
length) a Paramoecium. Note and label: 

a. Ectosarc, the clear outer layer of cytoplasm. 

b. Endosarc, the more granular inner cytoplasm. 

c. Peristome, the fring of cilia, around the mouth or opening 
to the gullet or oesophagus. 

d. Cilia, the delicate hair-like projections of the body wall. 

e. Gullet or oesophagus, the tube leading from the peristome into 
the body. 

f. Oral groove, the oblique groove on the side of the body. 

g. Meganucleus, the large elongate nucleus near the center of 
the body. 

h. Micronucleus, the small nucleus just beside the meganu- 
cleus. 

i. Contractile vacuoles, two clear spaces, one near each end of the 
body. These vacuoles alternately, and rather regularly, contract 
and as they do so, from six to ten radiating canals may be seen 
extending in all directions from the center. 

c. Vorticella. This is a Protozoan often found adhering to 
submerged twigs and leaves, and can usually be obtained by placing 
the trash from a pond or pool into jars and letting it stand in the 
room for a few hours. Vorticella commonly occurs in groups. 

1. Mount on a glass slide a bit of vegetable substance from water 
containing Vorticella and examine it first under the low power and 
then under the high power. Study an individual organism and note 
that it is made up of a bell-shaped body and a long slender stalk. 
The stalks will be attached to some object and may be either con- 
tracted or extended. When extended the stalk is very slender and 
hair-like, but when contracted it is coiled up, somewhat in the 
manner of a spring. 

2. Study and Observe the Following: — • 

a. The contraction and extension of the stalk. (This may re- 
quire slight jarring or tapping of the slide). 

b. The closing and opening of the peristome, a flaring rim or 
flange. 

c. The action of the cilia and the effect on free particles in the 
water. 



21 

d. A curved, often horse-shoe-shaped, nucleus (meganucleus) 
near the center of the body. This is best distinguished by stain- 
ing with methyl green or iodine. 

e. A clear contractile vacuole, near the nucleus, periodically 
appearing and disappearing. 

f. Food balls or food vacuoles within the endosarc. 

3. Draw a group of vorticella showing individuals in various 
positions. 

Draw on a large scale a single specimen and label : body, stalk, 
peristome, cilia, nucleus, contractile vacuole, and food vacuole. 

Summary 

1. Define Protozoa. 

2. What are the four classes of Protozoa? Give an example under each 
class. 

3. What is the economic importance of Protozoa? 

4. What characters distinguish the Protozoa studied in the laboratory? 

5. In what way is Paramoecium more highly developed or organized than 
Amoeba? 

6. What is the relative thickness of Paramoecium to its length? 
7 Of Amoeba? 



EXERCISE 5 
PHYSIOLOGY OF THE CELL 

References. Needham, General Biology, pp. 82-92; Coulter, Barnes and 
Cowles, A Textbook of Botany, Vol. 1, part II, Physiology; Palladin, V. A., 
Plant Physiology; Huley, Thomas H., Lessons in Elementary Physiology; 
Verworn, Max, General Physiology. 

Material and Apparatus Needed. Compound microscope, glass slides, cover 
glasses, forceps, ruler, test tubes, tumblers, petri dishes, salt solution, copper sul- 
phate solution and crystals, crystals of potassium ferrocyanide, 95% alcohol, Spi- 
rogyra, Elodea, potato strips, strips of gelatine. 

Physiology is the study of the life process or functions in living organisms. The 
fundamental physiological processes in both plants and animals are very much 
alike. In the simpler plants and animals the individual cell carries on all of the 
essential life processes associated with growth and reproduction. In the more 
complex organisms cells or tissues are differentiated in structure or function, or 
both. All living organisms exhibit certain properties which distinguish them from 
non-living matter. Among these may be mentioned automotism, metabolism, 
reproduction, adaptive response to environment etc. Only a few of the functions 
of living organisms will be studied in this exercise. 



LABORATORY EXERCISE 

a. Movement of Protoplasm. On a glass slide in a drop of water 
mount a young green leaf of Elodea and cover with a cover glass. 
(Chara or Nitella may be substituted if necessary) . Examine under 
low power and note the structure of the leaf. Note that it is made up 
of a number of cells. Under the high power note the numerous 
chloroplasts in the cell. Look for the movement of cytoplasm in 
some of the cells. The cytoplasm is so nearly transparent that it 
would be impossible to see the movement if it were not for the 
chloroplasts imbedded therein. The chloroplasts are carried along 
in the protoplasmic stream and the movement is therefore apparent 
only because of the moving chloroplasts. Note the time required for 
a complete rotation. Compare the rate and direction of rotation in 
adjacent cells. Calculate the rate of movement of the cytoplasm in 
millimeters per hour. (The instructor will give the measurements 
of the cell.) Record all results. Draw a cell (2 inches in length) and 
indicate by arrows the direction of the cytoplasmic movement. 

b. Diffusion. Into a test tube half filled with water drop a 
small crystal of copper sulphate. Set the tube aside and at the end 

22 



23 

of the laboratory period examine to see what has taken place. Why 
is not the entire solution equally colored ? What will be the result if 
you leave the test tube undisturbed for a period of five ar six days ? 
If feasible this should be done and the results recorded in the note 
book the following week. 

c. Osmosis and Osmotic Pressure. Osmosis is the diffusion of 
water or any other solvent through a semipermeable membrane from 
a region of low concentration of solute to a region of high concentra- 
tion of solute. The pressure developed by the entrance of this water 
is called osmotic pressure. 

1. Observe the demonstration experiment. A strong solution 
of sugar, 20%, has been placed in the semipermeable membrane of 
artificial parchment. Water, diffuses from a region of pure water 
(100% H 2 0) to a region of lower water concentration, (80%) 
developing a pressure which raises a column of water or which 
would burst the membrane if left stoppered. 

Sketch the apparatus used, label all parts and show what takes 
place. 

2. Growth of a Chemical Cell. In a test tube half filled 
with a 1% solution of copper sulphate (CuS0 4 ) drop a crystal of 
potassium ferrocyanide (K 4 Fe(CN) 6 ). Place the test tube in a rack 
or tumbler and watch the reactions. The two salts react producing 
copper ferrocyanide (Cu 2 Fe(CN) 6 ) and potassium sulphate (K 2 S0 4 ). 
The copper ferrocyanide forms a rather tough membrane which is 
semipermeable, being permeable to water and relatively imperme- 
able to solutes. Because of the high concentration of salt within 
the membrane due to the dissolving of the crystal, water diffuses 
into the membrane developing a pressure which bursts the cell. 
On bursting, the inner solution of potassium ferrocyanide comes 
in contact with the outer solution of copper sulphate. The reaction 
immediately forms a new membrane which again closes the cell. 
How long will this growth continue? Note especially that only water 
and not the solution of copper sulphate enters the cell. If the solu- 
tion entered, the internal solution would not be pale yellow, but 
would be filled with a brown precipitate of copper ferrocyanide. 
Note. Remember this is a chemical reaction of non-living matter 
and is used only to show the formation and growth of a dead 
cell with a semipermeable membrane, and does not carry with 
it any other processes incident to a living cell. 



24 

d. Plasmolysis. If the concentration of solutes is greater within 
the cell than outside, water will enter under pressure and the cell will 
be turgid due to endosmosis. If the concentration of solutes is greater 
outside of the cell, water will diffuse out and the cell will collapse, or 
become plasmolyzed due to exosmosis. Place a few strands of 
spirogyra (or strips from the under epidermis over the midrib of the 
leaf of Zebrina pendula) on a glass slide in a drop of 1% solution of 
salt (NaCl). Cover with cover glass and examine under low and 
high power. Note the position of the cell contents. Immediately 
replace the salt solution with fresh water. What change do you 
observe? Explain. Draw a normal and a plasmolyzed cell showing 
the relative positions of the contents. 

e. Turgor. Examine strips of potato tissue that have stood over 
night in salt solutions of different concentrations, 1%, X% and 0%. 
Measure and record the length of these strips and also note which are 
the most turgid and which are the most flaccid. Each strip was 5 cm. 
long when placed in the solutions. Explain the results. What keeps 
the strip turgid f Place the most turgid strip in the solution from which 
the most flaccid strip was taken and the most flaccid strip in the one 
where the turgid strip was. Measure and test turgidity at the end of 
about an hour. Record your results. 

f. Colloidal Hydration or Imbibition. Many colloidal sub- 
stances such as gelatin, starch, cellulose, proteins, etc., will absorb 
water and swell. Measure the strip of gelatin provided, then place 
it in a petri dish or watch glass of water. After 15-20 minutes (not 
longer) measure and note the increase in length. This swelling is 
due to colloidal hydration. Now place the swollen strip in a dish 
of 95% alcohol and note the effect on the length. Record all results. 
This is a crude experiment indicating how a muscle may contract due 
to loss of water and elongate on its reabsorption. 

Summary 

1. What holds a succulent green plant erect? 

2. Why do plants wilt? 

3. Why does a strip of potato which has been placed in a salt solution become 
flaccid. 

4. What is a semipermeable membrane? 

5. What is the function of water in plants? 



EXERCISE 6 
FLAGELLATES, THE INTERMEDIATE ORGANISMS 

References. Needham, General Biology, pp. 104-109; Parker & Haswell, 
Textbook of Zoology Vol. I; Coulter, Barnes & Cowles, A Textbook of Botany. 

Material and Apparatus Needed. Compound microscope, glass slides, 
cover glasses, pipette, copper sulphate solution, iodine solution, and cultures of 
Euglena and other Flagellates. 

The group Flagellata, or whip bearing organisms, is a very large one contain- 
ing an immense number of forms most of which are extremely minute. The 
genera and species of this group show a wonderful diversity in structure and 
habit. The one character common to them all is the presence of one or more 
flagella. Some flagellates are so plant like in character that they are claimed as 
plants by many botanists; others are hardly to be distinguished from animals. 
In structure they vary from single celled forms to colonial forms in which the 
colonies are made up of many cells. 



LABORATORY EXERCISE 

a. Euglena. This is one of the largest Flagellates and is com- 
posed of a single cell. Euglenae are found in ditches and temporary 
pools, where, when present in large numbers, they often color the 
water green or form a greenish deposit upon the sides and bottoms 
of the pools. 

1. From the material in the jars on the supply table take a 
small drop of water containing Euglenae, and place it on a clean 
slide in a flattened drop, made by spreading out the water with the 
tip of the pipette. Do not put on a coverglass. Examine under 
low power for living Euglenae. Note the mode of swimming. 
Which is the anterior end? The anterior end bears the propelling 
mechanism, the flagellum. This structure cannot be seen until 
the specimen is stained. Does Euglena rotate, like Paramoecium, 
as it swims? Watch the activities of Euglena for 10 or 15 min- 
utes and then describe carefully the manner of swimming. 

2. Measurement of Euglena. To gain an appreciation of 
the size of Euglena, place in the mount on the slide, a hair from 
your head. The average diameter of the human hair is 50 microns, 
or 1 /20 of a millimeter. Watch the Euglenae as they swim near 
the hair and record the average length and width of the specimens. 
In your drawing (called for in the next paragraph) be sure to 
make your relative dimensions correct. 

25 



26 

3. Cover the mount with a coverglass and examine the Eu- 
glenae under high power. If they do not remain quiet add a 
tiny drop of copper sulphate solution. This kills the specimen 
without staining it. 

Make a drawing of the Euglena at least 3 inches long. Label the 
following parts: 

a. Mouth, the short channel-like opening in the anterior end 
of the body. 

b. Pulsating vacuole, just posterior to the mouth. It appears 
as a clear globule-like space in the body plasm (endoplasm). 

c. The red eye-spot or stigma, the organ sensitive to light, 
lying near the contractile vacuole. It is usually red but may 
appear as a blackish speck. 

d. Chromotophores, the bright green oval refringeat bodies 
distributed throughout the organism. Determine whether one 
or several or any definite number of chromotophores are present. 
Are the chromotophores in any way connected with each other? 

e. The nucleus near the center of the body. If this is not 
visible in the living specimen note it in the stained specimen. 
(See under f.) 

f . The flagellum or cilium at the forward end of the body. 
In order to be able to discern the nucleus and flagellum clearly, 
make a fresh mount of Euglena and before putting on the cover- 
glass add a small drop of the iodine solution. This will stain 
the flagellum and nucleus. 

4. Make a series of 4 or 5 outline drawings to show the different 
shapes which Euglena may assume. This series should include a 
spherical or globular form, the encysted or resting stage. 

b. Other Flagellates. Observe other flagellates which the in- 
structor will provide and follow the directions given. 

Summary 

1. What is the probable relation of the Flagellates to plants? 

2. What are their animal characteristics? 

3. Their plant characteristics? 

4. Name four flagellates. 

5. How does Euglena obtain its nourishment? 



EXERCISE 7 
BACTERIA AND FUNGI 

References. Needham, General Biology pp. 92-101; Jordan, General 
Bacteriology; Conn, The Story of Germ Life; Coulter, Barnes and Cowles, A 
Text-book of Botany; Atkinson, Mushrooms; etc. 

Material and Apparatus Needed. Compound microscope, glass slides, 
cover glasses, forceps, dissecting needles, hay infusion, cultures of bacteria, 
clover plants, black mold on bread, blue mold on fruit etc. 

I. BACTERIA 

Bacteria are the simplest as well as the smallest of all known living organisms. 
They occur almost literally everywhere. The cells are either solitary or they 
may form filaments or they may cling together in masses so as to suggest colonial 
forms. Bacteria vary greatly in shape and form but in general they may be 
grouped under three types; (a) spherical or coccus; (b) rod-shaped or bacillus, 
(c) curved or spiral (spirillum). On account of the minuteness in size practically 
no internal structure can be made out, even under the best microscopes. Some 
bacteria have flagella. These can only be seen. after the specimens have been 
carefully stained by special technique. 

LABORATORY EXERCISE 

a. Bacteria on Potato. These potato slices were partially 
sterilized by steaming them for about five minutes. This kills most 
of the fungus spores but does not kill the spores of the spore-forming 
bacteria. The potato slices were then incubated for several days at 
blood temperature. 

1. Examine the slice of potato in the petri dish and note the 
different colored growths or colonies on the surface of the slice. 
In what other ways do they differ? List the likenesses and 
differences in the growths. 

2. Draw an outline of the potato slice and show the structure 
of the different growths present, the location and relative size of 
the colonies. 

3. In a drop of clean water mount on different slides a bit of 
growth from different colonies of bacteria. Cover with a cover 
glass and examine under high power. 

a. Note form, size, arrangement and whether or not the 
bacteria are motile. Do these organisms exhibit any evidence 
of chlorophyll? 

27 



28 

b. Draw the different forms of bacteria observed, specifying 
the type to which each belongs. None of these drawings should 
be under }4 inch in length or diameter. 

b. Bacteria in Hay Infusion. A hay infusion is prepared by 
placing some dead grass or leaves in a jar, covering this with water 
and allowing it to stand in a warm room for a week or so. A brown 
scum will form on the surface of the water and in this scum will 
usually be found myriads of bacteria. A very large spirillum is 
usually present in such infusions. 

1. Mount a little bit of bacterial jelly from the surface of the 
hay infusion on a glass slide, cover and examine it for bacteria 
under high power. Make drawings of any types not previously 
seen in this laboratory period. 

c. Root-nodule Forming Bacteria. These are the nitrogen 
bacteria of the soil which are able to utilize the free nitrogen that 
exists in the air. They are best known in connection with the tu- 
bercles of certain plants belonging to the family Leguminosae, such 
as pea and clover. Such plants can therefore be used in the restora- 
tion of nitrogen compounds to impoverished soil. 

1. Examine the roots of the clover plants furnished and note 
the nodules of varying size. Make a drawing of a small part of the 
plant showing some of these nodules. 

2. Remove one of the nodules, place it on a glass slide in a 
drop of water and crush it under the cover glass. Examine under 
high power the material which has oozed out. Draw some of the 
bacteria. 

II. FUNGI 

This is an enormous assemblage of Thallophytes comprising the yeasts, 
molds, mildews, rusts, smuts, mushrooms, toadstools, and puffbails. Fungi range 
in size from the minute microscopic cells of the yeast plant to the highly organized 
body of the mushroom often of considerable size and extent. The group is char- 
acterized by the absence of chlorophyl; consequently they are either parasites or 
saprophites. 

LABORATORY EXERCISE 

a. Black Bread Mold (Rhizopus nigricans). This mold is 
easily obtained by allowing bread to remain a few days in a closed 
moist jar in a warm place. 

1. Examine a piece of bread on which the mold occurs. Note 
that the mold plant is made up of many white fleecy threads or 
filaments, called hyphae. (All the hyphae of a single mold plant 



29 

are collectively called the mycelium or thallus.) Do these hyphae 
occur only on top of the bread or do they also penetrate into the 
bread below the surface? Where do these plants obtain their 
nourishment ? 

2. Mount in a drop of water on a glass slide a small quantity 
of the mycellium of the bread mold. Cover with a cover glass and 
examine under low and high power. 

Note : — 

a. Mycelium, the much branched thread-like structures. 
What is inside these mycelial tubes or hyphae? Are the my- 
celial branches divided into cells by cross walls? 

b. Cytoplasm, within the hyphae. Are any vacuoles present ? 

c. The delicate cell wall of the hyphae. 

d. Sporangiophores , the filaments which bear at the end the 
sporangia or reproductive bodies. 

e. Sporangia, the enlarged rounded reproductive bodies at 
the tip of the sporangiophores. 

f. Spores, the small reproductive cells within the sporangia. 
The spores correspond to the seeds in the higher plants. 

g. Columella, the dome-shaped enlarged tip of the filament 
around which the sporangium is formed. 

h. Rhizoids, the branching filaments at the base of a group 
(stolon) of sporangiophores. What is the function of the 
rhizoids ? 

3. Make an enlarged drawing of a portion of the mold showing 
and labeling the following parts: mycelium, cytoplasm, cell wall, 
sporangiophore, sporangium, spores, columella, and rhizoids. 
b. Blue Mold (Pencillium). (If time permits). This is the 

mold which commonly occurs on preserves, lemons, oranges, bread 
etc. 

1. Examine a lemon or other article of food on which this 
mold occurs and in a few brief statements compare the structure 
and appearance of this mold with the black bread mold. 

2. Mount a little of the mold in a drop of water on a glass 
slide, cover with a cover glass, and examine under high power. 

Note: 

a. Mycelium. Are the mycelialbranches in this mold divided 
into cells by cross walls? 

b. Conidiophores. These are the sporebearing filaments which 
correspond to the sporangiophores in the black mold. In what 



30 

way do the conidiophores differ from the sporangiophores in 
black mold? 

c. Conidia. These are the spores at the end of the coni- 
diophores. How many conidia do you find at the end of one 
filament ? 

3. Draw as in black mold, and label: mycelium, conidiophore 
and conidia. 

Summary 

1. What strikes you as the most distinctive characters of bacteria and fungi, 
as setting them apart from each other and from the algae? 

2. Why can not bacteria and fungi develop in water alone which would permit 
growth of algae? 

3. Cite three definite instances in which bacteria are of benefit to man. 

4. In what manner do bacteria reproduce? 

5. What is a parasitic fungus? A saprophytic fungus? 



EXERCISE 8 
REPRODUCTION AMONG THE SIMPLER ORGANISMS 

References. Needham, General Biology, pp. 109-115; Coulter, The Evo- 
lution of Sex in Plants; Coulter, Barnes and Cowles, Textbook of Botany Vol. 
I; Bergen and Davis, Principals of Botany; Hegner, College Zoology; Parker 
and Haswell, A Textbook of Zoology, Vol. I. 

Material and Apparatus Needed. Compound microscope, slides, cover 
glasses; cultures of pleurococcus, yeast, paramoecia, black mold; live earth- 
worms, fruiting chara, conjugating spirogyra, and prepared slides of budding 
hydra, dividing and conjugating paramoecia. 

Reproduction is the process by which plants and animals give rise to offspring. 
It consists essentially of the separation or setting apart a portion of the living 
substance of the parents body and its subsequent growth and differentiation 
into a new individual. The reproduction may be asexual, in which case the 
offspring is derived from a single parent; or it may be sexual, the offspring being 
commonly derived from two parents. 

LABORATORY EXERCISE 

ASEXUAL REPRODUCTION 

This is division without cell union and is represented by at least 
three different types. 

1. Division by Fission. Reproduction takes place by binary 
fission each cell dividing into two equal parts. 

a. Plants. Pleurococcus or some other unicellular alga. 
Mount a small drop of the culture on a glass slide, cover and 
examine under the microscope. Make a drawing showing cells 
in the process of division. 

b. Animals. Paramoecium or some other protozoan. 
Mount a small drop of Paramoecia culture on a slide and ex- 
amine under low power for individuals which are undergoing 
division. Such individuals are characterized by the presence 
of a transverse constriction about the middle of the body. If 
dividing animals are found note the place and depth of the 
constriction. How many contractile vacuoles are present? 

Examine stained specimens under both powers of the microscope 
and determine what becomes of the meganucleus and micro- 
nucleus. Make a drawing of a Paramoecium in the process of 
division. This drawing should be at least three inches in length 

31 



32 

and should show very clearly the condition of the mega — and 
micronucleus. Label all parts shown. 

II. Division by Budding. Reproduction takes place by the 
protuberance of a portion of the cell or body of an organism, which then 
develops into a new individual. 

a. Plants. Yeast. Mount a small drop of yeast culture on 
a glass slide, cover and examine under the high power. Draw 
yeast cells, showing both single and budding cells. The drawing 
of each cell should be at least one inch in diameter. 

b. Animals. Hydra. This is a metazoan animal made up 
of tissues. Examine a budding hydra under low power and note 
that the bud is produced by the outpushing of the body wall 
which is composed of two layers of cells. The body cavity of the 
parent and bud is therefore continuous. A bud thus formed de- 
velopes a mouth and tentacles and when fully formed, it breaks 
loose and functions as a new individual. Make an outline drawing 
of a hydra with bud. 

III. Division by Spore Formation. Certain cells set aside for 
reproducing new individuals. 

a. Plants. Black Mold. This plant has been studied in a 
previous laboratory period and need not be taken up again. It 
illustrates one type of spore formation in the fungi. 

b. Animals. Monocystis. This is a parasitic protozoan 
(Sporozoa) found in the seminal vesicles of the earthworm. Ex- 
amine a slide, containing these specimens, under low and high power 
and look for the sporocysts. These spores have been produced by 
numerous divisions of a single cell. Make a drawing of a sporocyst 
showing the spores within. Record in your notes your estimate 
of the number of spores present in each cyst. 

SEXUAL REPRODUCTION 

Division, in sexual reproduction, is preceded or accompanied by 
the union of two cells. These cells which unite are called gametes. 
When the gametes are similar or identical they unite to form a zygo- 
spore. When they are dissimilar, composed of sperm and egg cell, 
they unite to form the fertilized egg. 

I. Plants. 

a. Spirogyra. Examine preserved material of Spirogyra. 
Note the various stages in the process of conjugation. The cells 



33 

of adjacent filaments each push out conjugating tubes. These 
tubes fuse as soon as they come in contact with each other. The 
protoplast (cell contents) of one cell passes through the conju- 
gating tube into the connected cell, the two protoplasts fuse and 
form a thick walled oblong zygospore. Make at least two drawings 
of the cells of spirogyra showing conjugation in different stages of 
the process. 

b. Chara. This plant is much more highly organized than 
Spirogyra, the reproductive bodies being highly complex structures 
differentiated into definite male and female organs, the male 
organs being known as aniheridia or spermaries, and the female 
organs as oogonia or ovaries. The reproductive organs are lo- 
cated at the nodes of the plant and are visible to the unaided eye, 
the mature antheridia being orange red. 

Examine under low power a small branch of Chara. Look for the 
reproductive bodies at the node and note: — 

1. The oogonium. An elongate oval body surrounded by 
spiral elongate cells. Above the oogonium each of these spiral 
cells cuts of a tip cell, the cluster of tip cells forming the crown. 
The single ovum or egg cell is invested by these spiral cells. 

2. Antheridium. A globular body just beneath the oogonium. 
This is more complex in structure. The wall is composed of eight 
triangular, dentate, plate-like cells which are known as shields. 
Projecting into the body from the center of each shield is an elongate 
cell the manubrium which bears a terminal head cell. These 
head cells give rise to several similar cells and each ultimate cell 
produces a pair of long filaments. Each of these filaments con- 
sists of approximately 200 cells and each of these cells produces a 
single sperm. There may thus be produced from 20,000 to 50,000 
sperms by a single antheridium. 

Draw a small branch of Chara showing antheridium and arche- 
gonium. Crush an antheridium under a cover glass and note the 
large number of filaments present. Under high power look for the 
sperms in the cells of the filaments. 
II. Animals. 

Paramoecium. Examine Paramoecia cultures for individuals 
swirnming about in pairs. Such specimens are conjugating. 
Examine prepared slides. The essential part of this process con- 
sist of the exchange of portions of the micronuclei. The mega- 



34 

nuclei degenerate. After this exchange of micronuclear material, 
the Paramoecia separate and for a period again reproduce by 
fission. 

Make an outline drawing of two Paramoecia conjugating and 
show the nuclei in detail. 

Summary 

1. How many parents are concerned in asexual reproduction? 

2. In sexual reproduction? 

3. In what way does sexual reproduction differ in Spirogyra and Chara? 

4. Define gamete, zygospore, oogonium, antheridium. 



EXERCISE 9 
BRYOPHYTES (LIVERWORTS AND MOSSES) 

References. Needham, General Biology pp. 118-128; Coulter, Barnes and 
Cowles, Text book of Botany vol. I: 92-121; Grout, Mosses with a Hand-lens; 
Campbell, Mosses and Ferns: etc. 

Material and Apparatus Needed. Simple and compound microscopes, 
glass slides, dissecting instruments, fresh specimens of Conocephalus and Mar- 
chantia and either fresh or preserved specimens of Marchantia bearing sex 
organs; fresh specimens of Polytrichum showing gametophyte and sporophyte; 
prepared slides showing cross sections of the thallus of liverwort, slides showing 
archegonial discs with sporophyte. 

Bryophytes is a phylum of plants which comprises the liverworts and mosses. 
This group is much more highly organized than the Thallophytes. The liver- 
worts are related to the green algae on the one side and to the higher plants on 
the other. Through them the aerial habit of green plants has probably been 
established. In the Bryophytes we find division of labor, certain cells or tissues 
being set aside to perform definite functions. Here we also have a definite alter- 
nation of generations, asexual and sexual plants alternately producing each other. 

HEPATICAE— LIVERWORT 

Liverworts are commonly found growing in moist shady situations, although 
some species grow in more exposed places. 

LABORATORY EXERCISE 

a. Conocephalus or Marchantia. 

1. External Features. Study a small portion of the liver- 
wort and note that the main body of the plant is made up of a 
flattened leathery leaf-like body, the thallus. On the under side 
of the thallus look for the fine hair-like rhizoids which appear as 
little rootlets. These are the feeding organs of the plant and 
serve to absorb the moisture and mineral salts from the soil. 
Are the rhizoids equally distributed over the entire lower surface? 
Note also the short scales on the under side which serve to fasten 
the thallus to the soil. On the upper surface note under the simple 
microscope the irregular hexaognal areas, in the center of each of 
which there is a small opening, the pore. These areas are called 
pore areas. The pores open into the air chambers within the thallus 
and thus facilitate the diffusion of oxygen and carbon dioxide. 
Note also the manner of branching of the thallus and at the tip of 

35 



36 

the branches the growing point. There may also be present 
small cup shaped bodies on the upper surface of the thallus. These 
are special reproductive bodies which will be studied later. 

Draw a surface view of a portion of the thallus, twice natural 
size, showing its form, mode of branching, location of growing 
point, and some of the "breathing pores." 
2. Detailed Structure. 

a. Examine a prepared slide of the cross section of the thallus 
of the liverwort under low power. This will show the general 
cellular structure of the thallus. Make an outline drawing of the 
entire cross section showing the upper and lower surface, the 
rhizoids and scales. Label. 

b. Examine the cross section of the thallus under the high 
power. Find a place where the section has been cut through a 
pore and note: 

1. Upper epidermis, a single layer of cells on the upper 
surface, elevated in the region- of the pore. 

2. Assimilatory parenchyma, pear-shaped cells containing 
chloroplasts ; these cells are situated immediately underneath 
the epidermis where they may have direct communication with 
the air through the pores. 

3. Common parenchyma, large colorless cells composing the 
greater bulk of the thallus. These cells serve to give form and 
body to the thallus. 

4. Lower epidermis, the single layer of cell on the under side. 

5. Rhizoids, the root-like feeding organs composed of modi- 
fied lower epidermal cells. 

6. Scales, the outgrowths of the lower epidermis which serve 
to fasten the thallus to the soil. 

Draw on a large scale, a portion of the cross section of the 
thallus in the region of a pore showing detail of the cellular arrange- 
ment. Label: upper epidermis, pore, assimilartoy parenchyma, 
common parenchyma, lower epidermis, rhizoids, and scales, 
c. Reproduction. 

1. Vegetative. On the upper surface of the thallus of Mar- 
chantia look for little cup-shaped bodies, the cupules. Within 
the cupules are found small buds (gemmae) and these, when 
liberated, give rise to new thalli. This is a vegetative mode of 
reproduction. If any of these cupules are present in your specimen 
add one or more to your drawing (under a, 1). 



37 

2. Gametophyte Generation. Sexual reproduction is brought 
about in the gametophyte generation by the production of sperms 
in the male reproductive organ, called antkeridium ; and eggs in the 
female reproductive organ, called archegonium. The sperms, in 
the presence of water, find their way to the archegonia and there 
one sperm fertilizes each egg cell. 

Examine the thallus of Marchantia and note the branches arising 
therefrom. If the branch bears at the top a disc with a lobed margin 
it constitutes the male reproductive organ and is called the antheri- 
diopkore ; if the branch bears a disc with finger-like processes around 
the margin it constitutes the female reproductive organ and is called 
the archegoniophore. Make a drawing of a portion of the thallus 
showing antheridiophore and archegoniophore. 

3. Sporophyte Generation. The fertilized egg of the game- 
tophyte generation develops, not into a new thallus, but into a 
small, dependent, spore bearing plant, the sporophyte. 

Examine a prepared slide of the section of an archegonial disc of 
Conocephalus under the microscope and study the sporophyte in 
detail. 
Note: 

1. The tissue of the archegonial disc. (Gametophyte). 

2. The pear-shaped sporophyte with its base imbedded in the 
archegonial disc. The sporophyte is composed of three main 
regions : 

a. Foot, the base or attachment. 

b. Neck, the narrowed part of the sporophyte. 

c. Sporangium, the enlarged head which contains: 

1. Spores, the asexual reproductive cells. 

2. Elaters, sterile, elongate cells with spiral thickenings.' 
These, when they become moist, expand and thus aid in the 
scattering of the spores. 

These spores develop into a green thallus (gametophyte) . Make a 
large drawing of the section of an archegonial disc showing the sporo- 
phyte in detail. Label: gametophyte tissue, sporophyte, and in the 
sporophyte, foot, neck, sporangium, spores, and elaters. 

MUSCI— MOSSES 

The mosses include a group of Bryophytes comprising many more species 
than the liverworts. They are found in all situations except in salt water. 
The mosses, like the liverworts, have a definite alternation of generations, 
the gametophyte being produced from spores of the sporophyte generation, 
while the sporophyte is derived from the fertilized egg of gametophyte gener- 



38 

ation. In the mosses, however, the spore upon germinating first produces a 
branching filamentous agla-like structure which is called the protonema. 
This protonema then forms buds which give rise to the "leafy" moss plant. 
This intermediate structure, the protonema, is the distinguishing character of 
the mosses and liverworts. 

LABORATORY EXERCISE 

a. POLYTRICHUM. 

1. External Features. Study the moss plant and note that 
it is made up of an erect stem which bears numerous leaves on the 
upper portion. Note the many hair-like rhizoids at the basal part 
of the stem. These, as in liverworts, are the feeding organs. 
The leafy stem with the rhizoids is gametophyte and has developed 
from the protonema. Where did the protonema originate? The 
sex organs, archegonia and antheridia, are borne at the tip of the 
leafy stem. From the fertilized egg develops the stalked sporo- 
phyte which remains attached to the leafy stem. In the sporo- 
phyte note: — 

1. The long slender stalk. 

2. The capsule, (sporangium), the enlarged "head" of the stalk. 

3. The calyptra, the hairy scale-like body at the top of the 
capsule. This is part of the archegonium. How does it come 
to be at the top of the sporophyte? 

4. The cap (operculum), the cap-like structure on top of the 
capsule, better made out after the calyptra has been removed. 
Make a drawing of the entire moss plant indicating clearly which 
part is sporophyte, and which part is gametophyte. Label: stem, 
leaves, rhizoids, sporangium, operculum, and calyptra. 

5. Remove the operculum from the capsule and examine the 
top of the capsule with the simple microscope. Note that the 
edge of the capsule is provided with a fringe of incurving teeth. 
These teeth collectively constitute the peristome. Thefuncton of 
these teeth is to assist in the scattering of the spores. 

Draw the "mouth" of the capsule showing the teeth. 

Summary 

1. By a series of sketches properly labeled compare the life histories of the 
liverworts and mosses. 

2. What distinguishes liverworts from mosses? 

3. Which is more highly developed? Why? 

4. What is the difference between a spore and an oogonium? Between a 
zygospore and an oospore? 



EXERCISE 10 

PTERIDOPHYTES 

(Ferns, horse-tails, club mosses etc.) 

References. Needham, General Biology, pp. 128-136; Coulter, Barnes and 
Cowles, A Text-book of Botany Vol. I: 122-179; Campbell, Mosses and Ferns 
pp. 218-507; etc. 

Material and Apparatus Needed. Simple and compound microscopes, 
dissecting instruments, fern prothallia, young and mature sporophytes, pre- 
pared slides of cross section of rhizome, of cross section of leaflet and slides of 
prothallia. 

This phyllum includes the clubmosses, horse-tails, true ferns, etc. The club- 
mosses (ground pines) constitute about one-eight of the entire phyllum, the horse- 
tails (scouring rush) about 25 species and the true ferns more than 3000 species. 
The Pteriodphytes are distributed over the entire world being especially abundant 
in the tropics. 

LABORATORY EXERCISE 

The Fern (Pteris or Polypodium) . In the fern we have, as in the Bryophytes, 
a definite alternation of generations. The gametophyte generation is represented 
by a small, inconspicuous, short lived, heart-shaped plant body called prothallium. 
The sporophyte generation is represented by the large independent fern plant 
which is differentiated into stem, roots and leaves or fronds. 

I. Gametophyte Generation (Prothallium). This corre- 
sponds to the thallus body in the liverwort. It has developed from 
the spore. Prothallia may be obtained by sowing fern spores on 
moist soil in a box and covering with a piece of glass and allowing the 
box to remain in a lighted place at constant temperature. 

a. Examine the specimen of fern prothallium and note: — 

1. Shape, size and color. Describe. 

2. The notch in the margin of the prothallium. At the base of 
the notch is located the growing point. 

3. Rhizoids, on the under side of the prothallium. How do 
they compare with the rhizoids in the liverworts and mosses 
which you have studied. 

4. Archegonia, on the under side below the notch in which 
are developed the eggs. 

39 



40 

5. Antheridia, below the archegonia and more or less obscured 
by the rhizoids. In them are developed the sperms (anthero- 
zoids) . 
Draw on a large scale the ventral view of the fern prothallium 

showing and labeling; notch, growing point, rhizoids, archegonia and 

antheridia. 

b. Examine the prothallium under high power and draw on a 
large scale an aniheridium showing details of structure. 

c. If a section of an archegonium is available examine it under 
high power and make a detailed drawing showing the egg cell within. 

II. Sporophyte Generation. 

A. Young Sporophyte. Study the specimen provided and 
note that the sporophyte is attached to the under side of the pro- 
thallium. 

In this young sporophyte note: — ■ 

1. The developing stem or rhizome. 

2. The primary root and probably secondary roots. 

3. The primary leaf (frond). 

Make a drawing of the young sporophyte and gametophyte which 
is still attached to the developing sporophyte. Designate clearly 
which is sporphypte and which gametophyte. In the sporophyte 
label, stem, root and leaf. 

B. Mature Sporophyte. 

a. Study the mature sporophyhte and note its complexity of 
structure. 
Note : — 

1. Rhizome, the horizontal underground stem. 

2. Scales, the dark coverings over the entire surface of the 
" rhizome. 

3. Roots, attached to the rhizome. 

4. Fronds, the leaves. Study the manner of development 
of the frond (incurled tip), and the differentiation of the frond 
into a central leaf stalk and small leaflets which are called 
pinnae. 

5. Sori, the asexual reproductive bodies on the underside 
of the leaflets, each composed of a large number of sporangia. 

6. Indusium (in Pteris), a protective scale-like covering 
over the sporangia. 

Make a drawing of an entire mature sporpohyte showing the parts 
enumerated. Label: rhizome, scales, roots, fronds, pinnae and sori. 



41 

b. Sporangia. Scrape from the under side of a leaflet of the 
fern one of the clusters (sorus) of sporangia and mount some of the 
sporangia in a drop of water on a glass slide. Cover with a cover 
glass and examine under the microscope. 

In the individual sporangia note: — 

1. The stalk on which the sporangium is borne. 

2. The annulus, a single row or chain of cells with thickened 
walls surrounding the sporangium about two- thirds of the way. 

3. The irregular cells, thin walled and making up the greater 
portion of the wall of the sporangium. 

4. The spores, within the sporangium. 

Make an enlarged drawing of the sporangium showing and labeling 
all the parts enumerated. 

c. Rhizome. Examine under low power the prepared slide of 
the cross section of the rhizome and note: — 

1. Epidermis, the single outer layer of cells. 

2. Peripheral layer of supporting tissue, a thick layer of sup- 
porting cells just inside the epidermis. 

3. Inner supporting tissue, the dark transverse patches of 
supporting cells called sclerenchyma cells. 

4. The scattered vascular bundles in which are found the 
tracheids and sieve tubes which constitute the conducting tissue. 

5. The undifferentiated parenchyma cells which fill the re- 
mainder of the stem. 

Make a drawing of the entire cross section of the rhizome showing 
the arrangement of the layers of cells. Label all parts enumerated. 

d. Vascular Bundle. Under high power study the detailed 
structure of a single vacsular bundle and draw a small section 
of a bundle showing several cells in each layer. 

e. The Leaf. Strip off a bit of the lower epidermis of a leaflet, 
mount in water under the cover glass and examine under low 
power. 

Note : — 

1. Interlocking Epidermal Cells. These are quite irregular 
in outline. 

2. Stomates, the "breathing pores" of the leaf. 

3. Guard cells, the two bean-shaped cells, one on each side 
of the stomate. 

4. Chloroplasts within the guard cells and epidermal cells. 



42 

Make a drawing of part of the epidermis showing and labeling all 
the parts enumerated. 

f. Cross Section op Leaflet. Examine the prepared slide 
and note the arrangement of the different cells. 
Make a drawing of the cross section of the leaflet and label all the 
parts which you are able to identify. 

Summary 

1. In tabulated form compare by words and diagram the sporophyte and 
gametophyte generations in the liverwort, moss and fern which you have studied 
in the laboratory. 

2. What are the main features which distinguish the Pteridophytes from the 
Byrophytes? 

3. What is the function of the tracheids? Of the sieve tubes? 



EXERCISE 11 
COELENTERATES 

References. Needham, General Biology pp. 156-163; Hegner, College 
Zoology pp. 108-144; Parker and Haswell, Textbook of Zoology Vol. 1: 118-220; 
and other textbooks of Zoology. 

Material and Apparatus Needed. Compound microscope, forceps, pipette, 
watch glass, living hydra; prepared slide of hydra showing buds, spermary and 
ovary; prepared slides of cross section of hydra; prepared slides of Campanularia 
showing nutritive zooids and reproductive calycles. 

Coelenterata is a phylum of multicellular invertebrate, usually radially 
symmetrical, animals, including the corals, sea anemones, jelly fishes and hy- 
droids. They possess an internal digestive cavity. The body wall consists of 
two cellular layers, an ectoderm and an entoderm, between which is a gelatinous 
layer, the mesogloea. The coelenteron usually has a single opening or mouth 
surrounded by tentacles. The majority of Coelenterata possess nettling cells. 
The animals belonging to this phyllum, although much more complex than the 
Protozoa, are quite simple in structure, the body being composed of tissues only. 

HYDRA 

The hydra is a fresh water animal which lives in shallow ponds and permanent 
pools in still water. In warm weather it is often found near the surface, attached 
to the stems or reeds, or hanging from the lower surface of floating leaves. In 
winter it will more often be found attached to leaves that have fallen on the bot- 
tom. Its narrow, cylindrical body is about half an inch long, its tentacles are of 
equal length, and its color is pale brown (Hydra fusca), or, in another species, 
(Hydra viridis) clear green. Hydras may be obtained for class use by collecting 
leaves, sticks and plants from several fresh water pools and placing them in 
aquaria. The hydra, if present, will collect on the sides of the aquaria toward 
the light and may then be transferred, by means of a pipette, to watch glasses 
for study. 

LABORATORY EXERCISE 

a. Living Hydra. Study a living specimen in a watch glass 
containing a small amount of fresh clean water and note: — 

1. Shape. Elongated, cylindrical, with the body attached at 
its posterior or foot end, free at its anterior end, and crowned with 
a circle of long radiating tentacles. How many tentacles are there 
in your specimen? 

2. Color. 

3. Actions. Note the swaying about of the long tentacles in 
the water. These capture the food. Jar the watch glass a little 

43 



44 

and note that the hydra contracts until it is all lumped into a 
compact little mass. Do the tentacles contract and expand like 
the rest of the body? 

b.' External Structure. Examine hydra under the low power 
of the microscope and observe: — 

1. Foot, the end by which the hydra is attached. 

2. Tentacles, the radiating fingerlike processes at the distal end. 

3. Hypostome, the cone-shaped prominence at the anterior end, 
between the bases of the tentacles. 

4. Mouth, at the top of the hypostome. 

5. Nettling cells or cnidoblasts, the knob-like prominences on the 
tentacles. These are the defense organs of the hydra. 

6. Body wall, a double layer of cells, the outer transparent 
layer {ectoderm) and the inner darker layer {entoderm). 
Make two drawings of hydra (1) contracted; (2) extended. The 

drawing of the extended hydra should be at least 3 inches long. 
Show and label: foot, tentacles, hypostome, mouth, nettling cells, 
ectoderm and entoderm. 

c. Reproduction in Hydra. 

1. Budding. This has been observed in a previous laboratory 
period and need not be taken up again. 

2. Sexual. The sexual reproductive bodies are developed in 
low elevations upon the sides of the body. They are of two kinds 
and both may occur on the same individual. 

a. Spermaries or testes, conical, pointed elevations near the 
anterior end of the body, just below the tentacles, of varying 
number, each producing many sperms. 

b. Ovaries, rounded, obtuse elevations nearer the foot, 
rather larger than the spermaries, usually fewer in number, and 
each containing a single egg cell. 

Both spermaries and ovaries are developed from the ectoderm. 

Examine the prepared slides which show the reproductive organs. 

Add to your drawing of the extended hydra a spermary and an ovary. 

d. Cellular Structure. Examine under the microscope a 
prepared slide of the cross section of the body of hydra. Study the 
detailed cellular structure and note: — 

1. Ectoderm, the outer layer of cells. 

2. Entoderm, the inner layer of cells, composing about two- 
thirds of the body wall. Are all the cells alike in structure? 

3. Gastro-vascular cavity, the digestive cavity. 



45 

4. Mesogloea, a thin structureless substance which separates 
the ectoderm and entoderm. This will be stained as a deep blue 
line in your specimen. 

5. Interstitial cells, small cells at the bases of the larger ecto- 
dermal cells. 

6. Nettling cells, the stinging organs located in the ectoderm. 
Make a drawing of a small portion of the cross section of hydra 

showing the cellular structure in detail. Label : ectoderm, entoderm, 
gastro-vascular cavity, mesogloea, interstitial cells, and nettling 
cells. 

CAMPANULARIA 

This is a colonial form of Colenterate which lives in the sea, where it is 
found attached to rocks or plants. 

a. Examine the prepared slide under low power and note: 

1. General Structure. That the colony resembles the 
structure which would be formed by a budding hydra if the buds 
remained attached to the parent and in turn produced buds which 
would remain fixed. 

2. Nutritive zooid or hydranth, the hydra -like structures arising 
from the main stalk, and bearing at its end numerous tentacles. 
How many tentacles do you find on a hydranth? 

3. Reproductive calycles or gonangia, the reproductive organs 
which arise in the angles where the hydranths are attached to the 
main stalk (hydrocaulus) . Within the gonangia note the repro- 
ductive bodies or medusa-buds. 

4. Peris arc, the clear chitinous covering of the colony which 
serves to protect the soft parts. 

Make a drawing of a part of the colony of Campanularia showing 
and labeling, nutritive zooid, reproductive calycle, hydrocaulus, 
perisarc, tentacles and medusa-buds. 

Summary 

1. How do the cells of the ectoderm differ from the cells of the entoderm in 
hydra? 

2. What are the functions of the following in hydra: tentacles, nettling cells, 
ectoderm, entoderm, interstitial cells? 

3. What is radial symmetry? 

4. What methods of reproduction has hydra? 



EXERCISES 12 and 13 
ANNELIDA 

(Earthworms, leeches etc. Lumbricus Terrestris) 

References. Needham, General Biology, pp. 163-178; Hegner, College 
Zoology pp. 215-241; Parker & Haswell; Text-book of Zoology pp. 417-427; 
and other textbooks of Zoology. 

Material and Apparatus Needed. Compound and simple microscopes, 
dissecting instruments, trays, pins, live and preserved earthworms, prepared 
sections of ovary and of cross sections of the body of the earthworm. 

The phylum Annelida is a group of animals whose chief characters are: an 
elongate bilaterally symmetrical body composed of a series of segments or rings; 
usually with' a coelom or body cavity ; a vascular or circulatory system contain- 
ing red blood; a nervous system composed of a supra-oesophageal ganglion and 
a double ventral nerve cord; paired nephridia in some or most of the segments; 
and commonly having setae. 

THE EARTHWORM 

The earthworm is common in garden soil everywhere. It is strictly noc- 
turnal in its habits. Specimens for study may be obtained by digging, or at 
night, by the aid of a flashlight or lantern, they can be picked up when they 
are out of their burrows and extended on the ground. 

LABORATORY EXERCISE 

a. General External Characters. Examine both the living 
and the preserved specimens and note the following: 

1. Shape, the long cylindrical body which is divided by trans- 
verse constrictions into segments or somites. There may be more 
than three hundred of these segments. 

2. Anterior end, the end at which the segments are larger and 
more rotund, and which is tapering and bluntly pointed. 

3. Posterior end, the end which is flattened and obtusely pointed. 

4. Dorsal surface, which is convex, brownish red and with a 
median darker line. 

5. Ventral surface, which is flat and whitish. 

6. Locomotor setae, the bristles on the ventral surface of the 
segments, two pairs on each side, Draw the specimen over the 
back of the hand or arm and determine the location of the setae. 
Examine under simple microscope. 

7. Cuticle, the delicate iridescent membrane investing the entire 
external surface. 

46 



47 

8. Prostomium, the minute ball-like knob at the extreme 
anterior end. This is not a true segment, but forms a sort of 
upper lip for the mouth, which is situated just below and behind 
it. In numbering the segments, the one just behind the pro- 
stomium is counted as the first. 

9. Clitellum, the saddle-like swelling between the thirtieth 
and fortieth segments (counted from the front) . Its exact position 
varies slightly. How many segments does it cover in your speci- 
men? 

10. Apertures. 

a. Mouth, at the anterior end, below the prostomium. 

b. Anus, the small opening, at the posterior end of the body, 
which terminates the digestive tract. 

c. Dorsal or peritoneal pores, (probably not visible in your 
specimen) a row of pores on the median dorsal line, one at the 
anterior edge of each segment. Through these pores is secreted 
the slimy fluid which commonly covers the body of the worm. 

d. Sexual Apertures. 

1. Openings of the sperm ducts, situated on the ventral 
surface of the fifteenth segment just outside of the inner row of 
setae. 

2. Openings of the oviducts, smaller similar apertures on 
the ventral surface of the fourteenth segment. (Not 
easily made out). 

3. Openings of the seminal receptacles, two pairs of pores on 
opposite sides of the median ventral line, a pair on the groove: 
between segments 9 and 10 and another pair on the groove 
between segments 10 and 11. (These openings are very 
difficult to see and need not be looked for at present). 

e. Nephridiopores, a pair of openings of the nephridia or 
excretory organs on the outer ventral margin of each segment 
except the first three and last one. (These will be seen in the 
prepared sections later) . 

Draw the ventral view of the first forty segments. Show and 
label : prostomium, mouth, clitellum, setae, openings of the sperm 
ducts, oviducts, and seminal receptacles. The instructor will 
point out in a diagram on the board the location of the openings of 
oviducts and seminal receptacles. 



48 

b. Internal Anatomy. Place the freshly killed or preserved 
specimen in the tray, dorsal side uppermost, and cover with water. 
Thrust one pin through the prostomium only, and another through 
the last segment, with the body slightly stretched between the pins. 
Handle specimens carefully. Follow directions closely and do not 
cut more than directed. 

Dissection. Carefully insert the point of the thin sharp scissors 
through the body wall at about the middle of the body a little to one 
side of the median dorsal line and cut backward to the posterior end 
and then forward to the anterior end being careful always to cut a 
little to one side of the median line and especially careful not to cut 
deep so as to injure the organs which lie beneath, and as you get to 
the anterior end not to injure the brain which lies just below the 
body wall in the third segment. At the middle of the body draw 
the edges of the cut apart, and observe the septa (or partitions) 
which extend transversely across the body cavity. Note that these 
-correspond in position with the depressions between segments seen 
on the exterior, and show internal segmentation. Observe that each 
septum is perforated in the center for the passage of the alimentary 
canal and other vessels. 

Beginning at the anterior end, cut the septa close to the body wall 
<on each side, and pin back the flaps. The pins should be slanted 
outward so as not to interfere with the work later. 

Internal Organs. 

1. Reproductive System. The earthworm is hermaphroditic, 

each individual producing both male and female reproductive 

organs. 

a. Sperm Vesicles. These are the three pairs of large 
white lobes between the- ninth and thirteenth segments. The 
posterior lobes are larger, they surround and overlap the oeso- 
phagus. The testes within the vesicles produce the sperma- 
tozoa which are then discharged into the vesicles where they 
undergo further development and where they then are stored. 

b. Sperm Receptacles. Two pairs of small, white round 
sacs situated between the ninth and tenth, and tenth and eleventh 
segments attached to the septa. These sacs open directly 
downward to the outside. In these organs the sperms from 
another individual are stored until the time when the eggs are 
laid. In order to see these receptacles, carefully push the sperm 
vesicles aside. 



49 

c. Testes. Two pairs of minute white bodies, one pair in 
segment ten, and the second pair in segment eleven, situated 
close to the median ventral line. They are covered or surrounded 
by the sperm vesicles and need not be looked for at this time. 
Behind the testes is a funnel-like opening which leads into a 
tube which leads backward through the septa and in segment 
twelve unites with a similar tube from the testes in segment 
eleven. This single tube or duct then passes backward to 
segment 15 where it opens through the ventral surface to the 
outside. This duct is known as the vas deferens. 

d. Ovaries. One pair of small bodies in segment thirteen, 
located on the ventral side near the middle line and attached 
to the septum which divides segments twelve and thirteen. 
Just posterior to the ovaries are found the funnel-like openings 
which lead into a short tube. This tube passes through the 
septum into the fourteenth segment where it enlarges to form 
the egg sac, and from this sac the tube passes through the ventral 
side and opens to the exterior on segment fourteen. This tube 
is called the oviduct. 

Examine the prepared slide of the ovary. On the sheet furnished 
you, complete the drawing by putting in the sperm vesicles and the 
sperm receptacles. Label: sperm vesicles, sperm receptacles, testes, 
vas deferens, ovaries, egg sac, and oviduct. 

2. Digestive System. Beginning at the anterior end study 

the digestive system or alimentary canal which extends the entire 

length of the body and note: — 

a. Buccal pouch, the thin- walled mouth cavity within the 
first three segments. 

b. Pharynx, the elongate, barrel-shaped, thick-walled por- 
tion extending from segment three to six. It is held in place 
by numerous radiating muscle fibers. 

c. Oesophagus, the long thin-walled tube, much smaller 
than the pharynx, extending from the seventh to about the 
fourteenth segment. This is in part hidden by the aortic 
arches and sperm vesicles. 

d. Crop, the small thin-walled pouch-like organ located in 
the fifteenth and sixteenth segments. 

e. Gizzard, the firm-walled, cylindrical organ located in the 
seventeenth and eighteenth segments. 



50 

f. Intestine, all that portion of the digestive tract which 

extends from the gizzard back to the posterior end where it 

opens to the exterior by the anus. 

On the sheet furnished, with the body outline drawn, draw the 

digestive system of the earthworm. Label: buccal pouch, pharynx, 

oesophagus, crop, gizzard and intestine. 

3. Circulatory System. In your specimen note: — 

a. Dorsal blood vessel, this is the reddish tube which lies on 
the dorsal surface of the alimentary canal closely united with it. 
In living specimens it can sometimes be seen to pulsate. 

b. Hearts or aortic arches, five pairs of large vessels encircling 
the oesophagus in segments seven to eleven, and connecting 
the dorsal vessel with the ventral vessel. They can be plainly 
seen by pushing the lobes of the sperm vesicles gently aside. 

c. Ventral blood vessel, (to be seen later) the small reddish 
tube extending along the ventral side of the alimentary canal. 

d. Subneural blood vessel, a longitudinal tube which lies 
below the nerve cord. 

e. Lateral-neural blood vessels, one longitudinal tube on each 
side of the nerve cord. 

Add to your drawing of the digestive system the following parts of 
the blood system: dorsal blood vessel and hearts. Label. 

4. Nervous System. Beginning at the posterior end care- 
fully remove with forceps the entire alimentary canal except the 
pharynx. Cut off the alimentary canal just back of the pharynx. 

Note : — 

a. Brain or supra-cescphageal ganglion, the white, bilobed 
structure in the third segment, resting on the buccal pouch. 

b. Ventral nerve-ccrd, the white cord just beneath the ven- 
tral blood vessel, extending the entire length of the body. 

c. Ganglia, the swellings of the cord in each segment. 

d. Lateral nerve fibers, the lateral branches which are given 
off from the ganglia in. each segment. 

e. Circum-pharyngeal connectives, the cords which extend 
down on each side from the brain to the ventral nerve cord, 
forming a nerve collar which completely encircles the pharynx. 

On the sheet furnished, with the body outline drawn, make a 
drawing of the nervous system. Show and label: brain, ventral 
nerve cord, ganglia, lateral nerve-fibers and circum-pharyngeal 
connectives. 



51 

5. Excretory System. 

a. Nephridia, (the excretory organs) little, tangled, whitish 
thread-like bodies, attached to the posterior side of each septum, 
one on each side of every body segment except the first three 
and the last one. Each of these organs opens to the exterior 
by a minute pore (nephridiopore) . Each opens internally at 
the end which floats free within the body cavity, by a minute 
ciliated orifice. These organs drain out waste and worn-out 
materials from the body. 

Select a segment in which the nephridia have not been dis- 
turbed and examine under low power. The nephridia are indi- 
cated in a few segments on the sheet which contains the drawing 
of the rproductive organs. Label them. 

6. Muscular System. Spread out part of the body wall 
perfectly flat, and pin it so. Observe its muscular lining. 

Note : — 

a. Longitudinal muscles, which in the fresh specimen show 
up as glistening strands running lengthwise on the inner surface 
of the body wall. 

b. Circular muscles, with a dissecting needle stir up some of 
the longitudinal muscles and observe the circular ones under- 
neath which run transversely to the long axis of the body. 

c. Other muscles are best observed in the prepared slides of 
the cross section of the worm. 



EXERCISE 14 

THE CELLULAR STRUCTURE OF THE EARTHWORM 

a. Cross Section Through the Region of the Intestine. 
Examine the prepared slide of the cross section under the simple 
microscope or under low power of the compound microscope. There 
are several sections on each slide, select the one most perfect. 

Determine which is dorsal and which ventral side. Note that the 
body is made up of two tubes, one within the other, — the inner one, 
the intestine; the outer one, the tube formed by the body wall, 
which is relatively thick. Between these two tubes is the body 
cavity (coelomic cavity) . 

Study in detail under compound microscope: 

1. The Body Wall. In the body wall note: 

a. Epidermis, the layer of polygonal-shaped cells forming the 
outer cellular layer of the body. The cuticle is on the outer surface 
of the epidermis and is secreted by it but is so delicate that it 
may not be possible to determine it in this exercise. 

b. Circular muscles, the narrow, continuous, circular band 
lying just inside of the epidermis. 

c. Longitudinal muscles, more or less feathery looking struc- 
tures situated just within the circular muscles. They occupy a 
much broader area than the circular muscles and are broken up 
into four areas, due to the insertion of the setae. 

d. Peritoneum, a very thin layer of cells, just inside the longi- 
tudinal muscles, lining the body cavity. 

2. The Intestine. This is the large darkly stained organ in the 
center of the section. It is also composed of four layers. Examine 
the intestine and note: 

a. Typhlosole, the deep, inward fold of the dorsal wall of the 
intestine. 

b. Digestive epithelium, the inner layer of slender cells, which 
lines the intestine. 

c. Circular muscles, a layer of muscles surrounding the di- 
gestive epithelium on the outside (toward the body cavity). 

d. Longitudinal muscles, isolated longitudinal muscle fibers, 
represented as small dots, outside of the circular muscles. 

e. Chloragogue cells (modified peritoneum), a thick layer of 
yellowish cells all around the intestine, lining the body cavity. 

52 



53 

3. Nerve Cord. The solid body between the intestine and the 
ventral body wall. In some of the sections there are lateral pro- 
longations from the cord. These are the lateral nerve 'fibers. 

4. Blood Vessels. 

a. Dorsal blood vessel, closely united to the intestine just above 
the typhlosole. 

b. Ventral blood vessel, located between the intestine and nerve 
cord. 

c. Sub-neural blood vessel, on the ventral side of the nerve cord. 

d. Lateral neural blood vessels, one on each side of the nerve 
cord. (Probably not visible in your section). 

5. Setae, the four pairs of minute bristles on the outer lower side, 
by which the animal moves. . 

6. Nepkridia, these are represented, by varying fragments, on 
each side, between the body wall and intestine. 

Make an outline drawing of the entire cross section of the earth- 
worm showing the form and position of the various layers of tissues 
and other organs. Do not attempt to show cellular detail. Label: 
body wall, intestine, typhlosole, nerve cord, dorsal blood vessel, 
ventral blood vessel, subneural blood vessel, nephridia and setae. 

Draw a portion of the body wall, showing cellular structure in 
detail. Label: epidermis, circular muscles, longitudinal muscles, 
and peritoneum. 

Draw a portion of the intestine, showing cellular structure in de- 
tail. Label: digestive epithelium, circular muscles, longitudinal 
muscles and chloragogue cells. 

b. Sperm Cells. Examine a drop of the fluid from the sperm 
vesicles and note the sperm cells in various stage of development. 



Summary 

1. List the organs in the earthworm which function in respiration, excretion, 
digestion, reproduction. 

2. In what way is the earthworm more highly specialized than the hydra? 

3. What are the functions of each of the four layers of the body wall? 

4. Of each of the four layers of the intestine? 

5. What is the purpose of the typhlosole? 



EXERCISE 15 
ARTHROPODA 

References Comstock, Manual for the Study of Insects; Folsom, Ento- 
mology; Comstock, An Introduction to Entomology; Hegner, College Zoology. 

Material and Apparatus Needed. Simple microscope, trays, dissecting 
instruments, pins, live or pickled grasshoppers. 

The phylum Arthropoda is composed of animals whose body is made up of a 
series of rings or segments, some or all of which bear jointed appendages. It 
includes the Crustacea (crayfish, crabs etc.), Arachnida (spiders, scorpions etc.), 
millipedes, centipedes, insects etc. 

This phylum includes more species than all other phyla combined. 

INSECTA {Grasshopper) 

An adult insect is an air-breathing arthropod whose body is divided into 
head, thorax and abdomen. It possesses one pair of antenna, three pairs of 
legs and usually one or two pairs of wings. 

The Grasshopper. Grasshoppers are common almost everywhere where green 
vegetation occurs. Specimens for study are usually preserved in alcohol or 
formalin. 

LABORATORY EXERCISE 

a. External Anatomy. 

1. General Structure. Examine the grasshopper and note: 

a. Exo skeleton, the hardened (chitinous) covering over the 
entire body. 

b. Division of body into: 

1. Head. 

2. Thorax, to which are attached the wings and legs. 

3. Abdomen. 

Make a drawing of a side view of the grasshopper. This drawing 
should be at least four inches long. Show and label: head, an- 
tennae, eyes, thorax, wings, legs and abdomen. 

2. The Head and its Appendages. Study the head and find 
the following parts: 

a. Antennae, the slender filaments or feelers at the upper 
part of the head. 

b. Compound eyes, the prominent eyes on the upper and 
outer portion of the head. Examine the surface of the eye with 
a lens and note that it is made up of numerous hexagonal areas 
called ommatidia. Examine a mount of this under the demon- 
stration microscope. 

54 



55 

c. Ocelli, three simple eyes located between the compound 
eyes in the front part of the face. 

d. Labrum, the upper lip which covers the other mouthparts. 
Make a drawing of the front view of the head and label antennae, 
compound eyes, ocelli, and labrum. 

e. Mouthparts. Study the mouthparts with especial care, 
for in the grasshopper all the typical mouthparts of an insect 
are present and well developed. Proceeding from the front 
find and separate the mouthparts and place them on a piece 
of paper as directed by the instructor. 

1. Labrum, the large lobed upper lip. 

2. Mandibles, two toothed horny jaws covered by the 
labrum. 

3. Maxillae, two jointed compound organs, each bearing 
at its summit three appendages: 

(1) The lacinia, the innermost part. 

(2) The galea, a spoonshaped lobe. 

(3) The maxillary palpus, a jointed, tactile organ. How 
many segments does it contain? 

4. Labium, the two-lobed lower lip, bearing a pair of joint- 
ed labial palpi. 

5. Tongue, a fleshy organ between and below the maxillae. 
After separating these mouthparts and arranging them in order 
on a piece of paper make an enlarged drawing of each of these mouth- 
parts and label the parts as indicated above. 

3. The Thorax and its Appendages. Note that the thorax 
is made up of three main regions : the prothorax, the large saddle- 
like part bearing below the first pair of legs; the mesothorax, 
bearing the front pair of wings and the middle pair of legs; the 
metathorax, bearing the hind wings and the last pair of legs. 

a. The Wings. Cut off the front wing and note that it is 
narrow and leathery in structure. The front wings in grass- 
hoppers are called tegmina. Now cut off the hind wing and note 
how it is folded. The hind wings are used in flight and the 
front wings serve as protecting covers when the grasshopper is 
at rest. Spread out the hind wing and pin it down. 

Make an outline drawing of the tegmina and the hind wing show- 
ing relative size. 

b. The Legs. Compare the first and second pairs of legs 
with the third pair, in color and surface markings, position, 



56 

size and use. Find in one of the hind legs the following seg- 
ments beginning at the point of attachment to the body. 

1. Coxa, the small globular joint. 

2. Trochanter, the second segment, smaller than the coxa 
and more readily seen from the inside. 

3. Femur, the large and most prominent part of the leg. 
Within this are the powerful muscles used for leaping. 

4. Tibia, the long slender segment bearing on the sides a 
double row of spines, and spurs at its lower end. 

5. Tarsus, the three end segments bearing pads below and 
the end segment bearing two claws, and a lobe (pulvillus) be- 
tween the claws. 

Make an enlarged drawing (side view) of one of the hind legs in 
its natural resting position and label the following parts: coxa, 
trochanter, femur, tibia, tarsus, pulvillus, spines, spurs, and claws. 

4. The Abdomen. Count the segments of the abdomen as 
seen on the ventral surface. In the female there are eight, and in 
the male nine. The abdomen of the female terminates in an 
ovipositor, having four subequal points, which are used for making 
holes in the ground for the reception of eggs. The four points are 
repeatedly pressed together, pushed into the ground, and there 
separated, thus pressing the earth aside until a hole is made of 
sufficient depth, when the eggs are deposited in the bottom. 
The abdomen of the male terminates in an enlarged rounded blunt 
point. 

On each side of the abdomen notice a longitudinal groove, and 
just above it a row of spiracles, the breathing pores. How many 
spiracles are there in the abdomen? In the thorax? 

On each side of the first abdominal segment note a semicircular 
depression, across which is stretched a thin membrane. This is the 
organ of hearing and is called tympanum. 

Make a drawing of the tympanum at least two inches in its great- 
est diameter. 

Summary 

1. Name 5 beneficial and 5 injurious arthropods. 

2. Distinguish between a spider and an insect. 

3. In what ways is the grasshopper more highly organized than the earth- 
worm. 



EXERCISE 16 
VERTEBRATES 
THE EMBRYOLOGY OR DEVELOPMENT OF THE FROG 

References. Needham, General Biology pp. 193-206; Holmes, Biology of 
the Frog pp. 81-120; Hegner, College Zoology pp. 506-510. 

Material and Apparatus Needed. Compound and simple microscopes, 
watch glasses, forceps, dissecting needles, successive stages of development of 
frog from the egg to the adult stage. 

Embryology is the study of the development of an individual from the egg to 
the adult stage. The embryology of the different groups of vertebrates is very 
similar. The frog serves as a very good example for the study of the successive 
developmental stages. 

LABORATORY EXERCISE 

Caution. The different stages of development have been care- 
fully sorted and put in vials each of which bears a label designating 
the stage which it contains. Be sure to return the contents to the 
properly labeled vials when through studying them. 

Study the following stages in the development of the frog. Pour 
the contents of a vial into a watch glass and examine under the 
simple microscope. 

1. One Cell Stage. Note that one half of the egg is colored 
black and the other half white. The black end is called the animal 
pole and the white end the vegetative pole. Note that the egg is 
surrounded by layers of jelly which serve as a protection for the 
eggs. How many layers are there? 

Draw a side view of the unsegmented egg with the animal pole 
toward the top. Label: animal pole, vegetative pole, jelly layers. 
The drawing of the egg should be one inch in diameter and the layers 
of jelly proportionate in size. 

2. Two Cell Stage. Note the groove which divides the egg 
into two equal halves. Is it equally deep all around? 

Draw, omitting the jelly layers. Label poles and groove. 

3. Four Cell Stage. Note how the grooves are placed with 
reference to each other and to the poles. Make a drawing of the 
egg in such a way that you show both grooves. Label poles. 

4. Eight Cell Stage. Note here the manner in which the 
grooves divide the egg into eight parts. Are the parts of equal size? 

57 



58 

Draw the eight cell stage. Label parts. 

5. Sixteen to Thirty-two Cell Stage. Cleavage or division 
takes place more rapidly in the region of the animal pole because 
the protoplasm is more dense there. The cells at the animal pole 
are therefore much smaller than those at the vegetative pole. Make 
a drawing of either a sixteen or thirty-two cell stage. Label poles. 

6. Morula or Blastula Stage. As cell division increases the 
cells become smaller and smaller until the whole egg appears some- 
what like a mulberry. A cavity appears near the center of the egg 
so that the egg becomes a hollow sphere called the blastula. Make a 
drawing of the blastula stage. 

7. Yolk Plug or Gastrula Stage. After the blastual stage has 
been formed the cells near the border of the black and white areas 
begin to be pushed inward along a crescentric line. This is called 
the blastopore. The crescentric line soon becomes a circle which in- 
closes a small area of the white which is known as the yolk plug. 
Make a drawing of this stage and label parts shown. 

8. Open Neural Groove Stage. On the upper surface of the 
embryo an elevation appears now and forms two parallel ridges 
called the neural folds. These folds are confluent in a loop, the 
wider part later forming the brain and the remainder the spinal cord. 
The groove between the neural folds is called the neural groove. 
Make a drawing of this stage. Label: neural groove, neural folds, 
anterior and posterior ends. 

9. Closed Neural Groove Stage. As development proceeds 
the embryo begins to elongate somewhat. The neural folds of the 
sides meet and fuse above the neural groove and thus form the 
neural tube. Draw the closed neural groove stage and label the 
parts shown. 

10. External Gill Stage. All the above stages take place 
while the egg remains within the jelly. About the eighth or ninth 
day the young embryo breaks through the layers of jelly and be- 
comes a free swimming tadpole. Note the long tail with its upper 
and lower fins. Above note the developing eyes, on the sides of the 
body the external tufted gills, and on the ventral side the mouth, 
and on each side and a little back of the mouth a sucker disc. Make a 
drawing of the ventral view of the tadpole showing and labeling mouth, 
sucker-discs, external gills. How many gills does your specimen 
have? 



59 

11. Internal Gill Stage. In addition to the external gills 
there are developed later four pairs of internal gills. The external 
gills then disappear and a fold called the operculum grows backward 
from the head and covers the gill region. On the left side of the 
body just back of the gill region is an opening, the spiracle. The 
water is taken in through the mouth, passed through the gill slits 
and then out through the spira^e. Make a drawing of the left side 
view of this stage and label all the parts shown. 

12. Transforming Tadpole. As the tadpole reaches the stage 
where it is transformed into the young frog it undergoes marked 
changes. The intestine, which in the tadpole is long and coiled, 
shortens, the mouth becomes much wider and the horny jaws of the 
tadpole stage are shed. The hind legs develop first as buds on each 
side at the base of the tail and gradually become fully formed. The 
fore legs develop underneath the skin. The left leg passes through 
the spiracle and the right one breaks through the wall of the oper- 
culum. The tail is reabsorbed by the body. As the lungs develop 
the internal gills are reabsorbed and the transforming tadpole be- 
gins to breathe air directly. 

Study the transforming tadpole and then make a drawing, ventral 
view, showing and labeling all the parts which you are able to find. 

13. The Brain of the Tadpole. Study the demonstration 
specimen showing the brain of the tadpole. 

Note the following: 

a. Olfactory lobes, the two anterior prolongations of the brain. 

b. Cerebral hemispheres, the pear-shaped lobes just back of the 
olfactory lobes. 

c. Optic lobes, the large globular lobes. 

d. Cerebellum, the narrow transverse fold of the brain just 
back of the optic lobes. 

e. Medulla, the part just back of the cerebellum. 

Draw the brain of the tadpole and label the parts just enum- 
erated. 



EXERCISES 17 and 18 

VERTEBRATES 

THE FROG (AMPHIBIA) 

References. Needham, General Biology pp. 179-220; Holmes, Biology, of 
the Frog; Hegner, College Zoology pp. 477-526 and other textbooks of Zoology. 

Material and Apparatus Needed. Simple and compound microscopes, 
dissecting instruments, trays, pins, live and freshly killed frogs. 

The Vertebrates constitute a comprehensive division of animals, containing 
all those with a back bone, or segmented spinal column (which is represented in 
the embryo by a notochord), together with a few obviously related but more 
primitive forms in which the back bone is represented by a notochord throughout 
life. It contains the mammals, birds, reptiles, amphibians, fishes etc. 

Frogs are commonly found in marshy places or near brooks and ponds. They 
spend part of the time on land and part in water. In the winter they hibernate 
in the mud in the bottom of ponds. In the spring and summer specimens for 
study may be obtained by collecting the frogs at night, with the aid of a light, 
along the edges of ponds and brooks In cold weather live specimens may be 
dredged up from the bottom of ponds or they may be obtained from dealers. 
By placing the frogs in a cool moist place they may be kept alive for a long period 
of time; for during the winter season they are normally inactive and take no 
food. 

LABORATORY EXERCISE 

1. Study of the Live Frog. Study the live frog and observe: 

a. The form of the body. 

b. The presence of well developed legs. 

c. The eyelids. Are they of one sort? Touch the eye gently 
with the point of the pencil and note the eyelids. 

d. The breathing, note especially the throat, nostrils and sides 
of the body. 

e. The tympanum, or eardrum, the circular tightly stretched 
membrane of the ear situated just back of the eyes. 

Make a drawing of the side view of the head showing eyes, mouth, 
nostrils and tympanum. 

2. Study of a Chloroformed Specimen. Note: 

a. Color and markings of body. Of what use? 

b. Character of the skin. Why is it kept moist? 

c. Size and shape of mouth. 

d. Eyes. How do the eyelids function? 

60 



61 

e. Structure of tympanic membrance. 

f. Nostrils. Note how these may be closed. For what pur- 
pose? 

g. Teeth, open mouth and note where they are. 
h. Tongue. Where is it attached? 

i. Note that the nostrils are connected with the mouth by a 

passage. Why? 

Enter the answers to the above questions in your laboratory 
book. 

3. Dissection of the Frog. Dissect the frog under water. 
Place the frog upon its back, thrust a pin through each leg, slightly 
stretching the body. Be careful not to cut too deeply. Cut through 
the skin along the median ventral line, from the mandible to the 
posterior end of the body. Make a second cut at right angles to the 
first, entirely across the middle of the ventral surface, and turn 
back the four flaps of the skin thus formed. This will expose the 
thin, muscular abdominal wall. Observe a dark vein showing through 
the abdominal muscle on the median line. Make a longitudinal 
cut through the body wall, a little to the left of the median line, so as 
to avoid injuring the vein and continue to cut forward to the shoulder 
girdle avoiding blood vessels below. Then cut along one side of the 
elongated median bone of this girdle without injuring it, cutting 
forward through the transverse bone to the base of the tongue. 
Now make a cut at right angles to the longitudinal axis of the body 
posterior to the bone (shoulder girdle) but over the anterior abdominal 
vein so as to leave this uninjured. Next cut down on the right 
side of the abdominal vein, which will now have attached to it the 
narrow strip of the abdominal wall. Turn back the edges of the 
incision and expose the organs. 

a. Internal Features. Without unduly disturbing the 

internal organs of the body study their relative position, shape and 

size. Find the following organs: 

1. Liver, which is the conspicuous large mottled reddish 
organ consisting of a large double lobe on the right side of the 
body, and of a smaller single lobe on the left side. 

2. Heart, In front of the liver and enclosed in a thin sac, the 
pericardium. Pinch up the pericardium with forceps and cut 
it away with the scissors. Cut away also its attachments to 
the body wall taking care not to cut the heart, blood vessels or 
other organs. 



62 

3. Lungs, the pinkish strawberry shaped organs in front of 
and under the lobes of the liver. By gently lifting the lobes of 
the liver the lungs may be exposed without injuring the other 
organs. 

4. Gall bladder, the greenish small organ attached to one of 
the lobes of the liver. Find a duct leading from the gall bladder 
to the intestine. This is the bile duct. 

5. Stomach, the whitish organ to the left of the liver, con- 
necting in front with the oesophagus and behind with the small 
intestine. 

6. Small intestine, coiled and of considerable length. 

7. Large intestine, the caudal enlarged portion of the in- 
testine. 

8. Pancreas, a light colored gland between the stomach and 
small intestine (duodenum) . 

9. Spleen, the dark red roundish organ near the beginning 
of the large intestine. 

10. Urinary bladder, the whitish bilobed bladder attached 
to the posterior part of the alimentary canal. 

Drawing. On the sheet which contains an outline drawing of the 
frog draw in position, as nearly as possible, and label the following 
parts: liver, heart, lungs, gall bladder, stomach, small intestine, 
large intestine, pancreas, spleen and urinary bladder. 

4. Circulatory System. The circulatory system is composed 
of the heart, the central organ of circulation, the arteries and veins. 
Study the circulatory system and note: 

a. The heart, composed of three divisions: 

1. Ventricle, the conical posterior division. 

2. Auricles, the two anterior, thin-walled divisions. 

b. Arterial System. This is the system of tubes which 
carries the blood to all parts of the body. In your specimen note : — 

1. Arterial trunk or bulbos arteriosus, the large cylindrical 
tube which arises from the anterior end of the ventricle, and 
passes obliquely forward across the uppermost auricle, soon 
dividing into two principal branches. 

2. Aortic arches, the two branches arising from the arterial 
trunk and each soon dividing into three arches: 

a. The anterior carotid artery, which goes forward to the 
head. 



63 

b. The posterior pulmo-cutaneous artery which lends one 
branch to the lung and the other to the skin. 

c. The lrger middle aortic arch which curves upward and 
then backward where it unites with its fellow to form the 
dorsal aorta. 

3. Dorsal aorta, which extends along the dorasl wall of the 
body. 

4. Coeliac artery, the artery which branches off from, the 
dorsal aorta and gives off subsequent branches to the liver, 
stomach and other organs of the body cavity. 

5. Renal arteries, the short branches from the dorsal aorta 
leading to the kidneys. 

6. Iliac arteries, the branches from the dorsal aorta which 
go to the hind legs. 

c. Venus System. The right auricle receives the blood 
from all parts of the body except from the lungs. The blood 
from the lungs is returned to the left auricle. Study the venus 
system and find the principal avenues by which the blood is re- 
turned to the heart, after being distributed throughout the tissues. 
Abdominal Vein. This is the vein that was seen through 
the thin abdominal wall before the body cavity was cut open. 
Trace this vein backward far enough to see the large femoral 
veins coming up from the hind legs. Trace the abdominal vein 
also forward. Observe that it soon leaves the body wall, and 
descends through the body cavity to the liver, where it branches,. 
• sending one branch to each lobe of that organ. This is the 
ventral route to the liver; there is also a dorsal route through 
the kidney. Turn the organs that cover the kidneys to one 
side, and find a longitudinal vein, renal portal vein, coming from 
the posterior end of the body cavity, and passing along the 
exteral margin of the kidney, and dividing up into numerous 
branches, which enter the mass of the kidney. Then find a 
corresponding set of venous branchlets coming from the inner 
side of the kidney, meeting branchlets from the other kidney, 
and uniting into another large vein, which proceeds forward to 
the heart, receiving important branches from the viscera at 
several points. This is the postcaval vein. Trace it to the heart. 
Then draw the liver backward, and turn the ventricle over 
forward, and see the large hepatic vein which conveys the 
blood from the liver into the venus sinus,--. said, thence 



64 

into the right auricle. Draw the heart gently backward, and 
see the two large veins, the precavae, which bring the blood into 
the same chamber from the anterior parts of the body. The 
blood flows from the auricle into the ventricle, and is forced out 
again, by the contraction of the ventricle, through the arterial 
trunk. 

From the lung a pulmonary vein conveys the aerated blood back 
to the left auricle of the heart, whence it passes into the ventricle, 
to be mixed with the venous current from the right auricle. 

Make a drawing of the heart and the main blood vessels showing 
and labeling the following: ventricle, left auricle, right auricle, 
arterial trunk, carotid artery, pulmo-cutaneous artery, aortic artery, 
precaval veins, pulmonary veins, and postcava. 

Make a drawing of the kidneys and the blood vessels associated 
with them. Show and label: renal portal vein, dorsal aorta, renal 
arteries and renal veins. 

5. The Digestive Tract and its Appendages. Beginning 
at the posterior end of the body, carefully dissect out and remove the 
digestive tract with its appendages. Be careful not to injure the 
other organs. After you have removed the entire tract with is 
•appendages spread it out so as to clearly show the relationships of 
all the parts. 

Make a drawing of the digestive tract and its appendages showing 
and labelling; pharynx, oesophagus, lungs, stomach, liver, gall 
bladder, pancreas, small intestine, large intestine, cloaca and urinary 
bladder. 

6. Reproductive System. A pair of digitate, yellow fatty 
bodies are attached to the dorsal wall of the body cavity, behind 
the stomach, and close beside the median line. The paired repro- 
ductive organs lie just posterior to these, — rounded yellow testes 
in the male, and folded or lobed, lighter colored ovaries in the female. 
In the breeding season, the ovaries may be found so distended with 
eggs as to fill most of the body cavity. The oviducts, which conve)- 
the eggs to the cloaca, are very long and much convoluted tubes, 
having no connection with the ovary, but opening by a funnel- 
shaped orifice into the body cavity near the oesophagus. 

7. Renal Excretory Organs. A pair of reddish brown kidneys 
lie on the dorsal side of the body cavity, near the cloaca; and ducts 



65 

from these pass to the large whitish bilobed urinary bladder, which 
occupies the extreme posterior end of the body cavity as already 
noticed. 

The small, roundish red body, dorsal to the cloaca, and near the 
anterior end of the kidneys, is the spleen. 

Make a drawing of the reproductive organs and the kidneys. 

8. The Nervous System. 

a. The Sympathetic System. Having removed the organs 
of the body, or by gently turning them to one side, observe the 
spinal column. Observe the white spinal nerves extending out 
from it, along the body wall, just beneath the smooth, transparent 
peritoneum. Note that each spinal nerve, near its origin, sends a 
branch ventrally into the body cavity to meet a very delicate 
nerve cord that extends longitudinally, ventral to the spinal 
column, and near the median plane of the body. Examine this 
nerve cord carefully with a lens to find the minute ganglionic 
swellings on it at its juncture with the branches of the spinal 
nerves. Find also minute nerves arising from its ganglia, and 
extending to the internal organs. Trace it forward to the head. 
Find another similar nerve cord on the outer side of the median 
plane. Find minute commissural nerves connecting the ganglia 
of the two chains. 

Make a drawing of several spinal nerves and a portion of the 
sympathetic system. Consult the demonstration dissection. 

b. The Cerebro-Spinal System. Remove the skin from 
above the cranium and from one side of the head. Cut away the 
bony roof of the cranium, taking great care not to injure the deli- 
cate brain underneath. By means of a pipette or gentle stream 
of water wash out the soft substance which covers the brain. 
Make out the following parts: 

1. Olfactory lobes, a pair of conical processes extending for- 
ward from the extreme anterior end, and tapering into the 
olfactory nerves. 

2. Cerebral hemispheres, the large white lobes behind the 
olfactory lobes which make up the cerebrum. 

3. Optic lobes, the large conspicuous rounded eminences, 
well marked off from each other, and from other parts. 

4. Cerebellum, sl single narrow transverse band of nervous 
tissue just back of the optic lobes. 



66 

5. Medulla, the portion of the nervous tissue just behind the 
cerebellum and in front of the spinal cord. 

6. Spinal cord, the nervous tissue found within the spinal 
column. 

Make a drawing of the brain and spinal cord as seen from the dorasl 
side. Label all parts enumerated above. 

Summary 

1. Make a cross section drawing of the frog through the region of the heart 
showing and labeling -all organs. 

2. What is the function of the following organs in the frog; liver, spleen, 
olfactory lobes, left auricle, kidneys, pancreas? 



EXERCISE 19 
HISTOLOGY OF THE FROG 

References. Needham, General Biology p. 208; Holmes, Biology of the 
Frog. 

Material and Apparatus Needed. Compound microscope, simple micro- 
scope, glass slides and cover glasses, live frogs; prepared slides of sections of the 
frog's skin, lung, kidney, and intestine. 

The Vertebrates are multicellular animals and all tissues can be resolved into 
cell units. In some of the tissues it is difficult to make out the individual cells 
but by special preparation of sectioning and staining it is possible to detect the 
cells and usually see the nuclei within. 

LABORATORY EXERCISE 

1. Circulation of the Blood in the Web of the Foot. Ex- 
amine the demonstration of the circulation of the blood in the web 
of the frog's foot. Note the numerous small tubes (capillaries) 
through which the corpuscles are carried by the blood plasma. 
Note the branching capillaries. Some of these branches are so small 
that the corpuscles must pass through them in a single file order. 

Make a drawing of a small portion of the web of the foot showing 
the capillaries and the blood corpuscles within. 

2. Blood. Place a small drop of frog's blood on a clean glass 
slide, cover with a cover glass and examine under high power of the 
microscope. 

Draw a few of the blood corpuscles. 

Now in like manner study a drop of human blood and draw sl few 
of the blood corpuscles. How do the corpuscles of man and cor- 
puscles of the frog compare as to: color, structure and size. Enter 
these notes in your notebook. 

3. Skin. Examine the prepared sections of the skin of the frog 
under the high power of the microscope. Note that the skin is 
made up of two main layers, epidermis and dermis. 

a. Epidermis (stained blue), is made up of there kinds of cells. 

1. Transverse or elongate and flattened cells. 

2. Columnar or elongate and upright cells. 

3. Startified cells or squarish cells several layers deep, lying 
between the transverse and columnar layers. 

b. In the dermis (stained pink), may be seen round structures 
or glands. (Look over the slide carefully and locate some glands 
where the ducts may be seen). These glands are of two types: 

67 



68 

1. Mucous Glands. The smaller and more abundant 
glands which pour a mucus upon the surface of the skin. The 
epithelium which forms the boundary of the gland is cellular. 
(The secretion stains bluish). 

2. Poison Glands. The larger and less regularly placed 
glands secrete a milky fluid which is said to be harmful to fish 
and other small animals. The epithelium which forms the 
boundary of these glands is non-cellular in appearance (The 
secretion stains yellow) . 

Draw a portion of the skin showing the layers and structures 
mentioned above and label each. 

4. Intestine. Examine the prepared slides of the cross section 
of the intestine and note: — 

a. On the outside a thin peritoneum. 

b. Longitudinal muscles. 

c. Circular muscles. 

d. Submucosa, a non-cellular substance in which occur blood 
vessles. 

e. The folded digestive epithelium made up of: 

1. Goblet cells, which possess a large vacuole and therefore 
appear empty. 

2. Absorptive cells, which are narrow with an oval nucleus. 
Draw a cross section of the intestine, showing details in a small 

portion, and label the structures noted above. 

5. Lung. 

a. Study the entire cross section of the lung under the simple 
microscope and note that it contains many open spaces. These 
are air spaces or alveoli. 

Make an outline drawing of the whole cross section of the lung and 
show the position of the air spaces. 

b. Study a single fold of the lung under the low power of the 
compound microscope and note : — 

1. That each air space is lined with a single layer of 
epithelial cells. 

2. That the fold between the air spaces is composed of the 
epithelial layer, and that between the epithelial layers lies a 
substance called connective tissue in which muscles and blood 
vessels are located. 

3. Locate the end of a fold and note the muscle and blood 
vessel situated there. 



69 

Make a drawing of a fold and label : epithelium, connective tissue, 
muscle, blood vessel. 
6. Kidney : 

a. Refer to the diagram of a cross section of the kidney on the 
blackboard, and note the various structures indicated. 

1. Bidder s canal. 

2. Collecting tubules. 

3. Uriniferous tubules. 

4. Ureter. 

5. Renal portal vein. 

6. Glomeruli. 

b. Study the cross section of the kidney under the compound 
microscope and note : — 

1. The uriniferous tubules. 

2. Glomeruli, the masses of bright cells. 

Copy the diagram. Draw either a cross section or a longitudinal 
section of a tubule showing the cellular epithelium. Draw a glomer- 
ulus. What is its relation to a tubule? 

Summary 

1. In what respect does the structure in cross section of the intestine in the 
frog resemble, and in what respect does it differ from that of the earthworm? 

2. What is the function of the kidneys? Of the blood? Of the mucous 
glands? 



EXERCISE 20 

HOMOLOGY 

References. Needham, General Biology pp. 223-230; Conn, Biology pp. 
364-370; Comstock, Manual for the study of Insects; Comstock, The Wings of 
Insects. 

Material and Apparatus Needed. Simple microscope; prepared slides of 
cranefly wings; sheets of insect wing diagrams. 

Homology is true likeness, — 'likeness in form of parts, origin of parts and 
relation of parts. "Two organs are homologous when composed of like parts in 
similar relations, each to each." Thus the hand of man is homologous to the 
forefoot of the frog because they are composed of essentially like parts in similar 
relations. If the relationship is only superficial, that is, similar in function or 
shape, it is called analogy. The wing of a bat and the wing of a butterfly are 
analogous, for their likeness is only in function and not in fundamental structure. 
The wing of the bat however is homologous to the wing of a bird because they 
both are built up of similar bones, muscles, etc. 

Nature affords numerous examples which may be used for a study of homologies, 
Entire skeletons or parts of skeletons of a series of different species of animals 
might well be used. Insects, being very common and numerous, serve especially 
well for such a study. Most insects are provided with one or two pairs of wings. 
These wings are membraneous and are thickened or strengthened along certain 
lines. These thickened lines are called veins and the system of veins in the wing 
is spoken of as venation. Although the wings of the different species of insects 
vary greatly in shape and arrangement of the veins there exists a definite relation- 
ship between them. Probably all the different types of insect wings have been 
derived from a common ancestor which is called the hypothetical wing. 

The following drawing, figure 3, represents the hypothetical wing. 




Fig. 3 — The hypothetical insect wing 



70 



71 

The veins of the wing can be grouped under two heads: first, longitudina 
veins, those that normally extend lengthwise of the wing; and second, cross 
veins; those that transversely connect one longitudinal vein to another. These 
veins are designated by names. There are eight principal longitudinal veins, 
some of which are branched toward the outer end. The names which are given 
to these veins are as follows: (with the abbreviations which are used). 

1. Costa = C 5. Cubitus = Cu 

2. Subcosta = Sc 6. 1st anal = 1st A 

3. Radius = R 7. 2nd anal = 2nd A 

4. Media = M 8. 3d anal = 3d A 

The subdivisions of these main longitudinal veins are indicated as shown in the 
figure of the hypothetical wing. 

There are five cross veins in the hypothetical wing and they are named as 
follows: (with their abbreviations). 

1 . humeral crossvein = h 

2. radial crossvein = r 

3. radio-medial crossvein = r-m 

4. medial crossvein — m 

5. medio-cubital crossvein = m-cu 

Modifications in the venation is brought about in two ways: first, by a re- 
duction in the number of veins, two or more veins may fuse into one, or one or more 
veins may atrophy or drop out; second, by the addition of more veins. The 
manner of designating modified veins will be explained by the instructor. 



LABORATORY EXERCISE 

1. Hypothetical Wing. Study the hypothetical wing and get 
acquainted with the system of naming the longitudinal veins and 
cross veins. Note that the longitudinal veins are designated by 
capital letters on the outside of the margin while the cross veins are 
designated by small letters within the wing. 

2. Examine the prepared slide of a cranefly wing (Tipula) under 
the simple microscope and make a drawing of it. Then try to homol- 
ogize the veins with the veins in the hypothetical wing. Note. 
The costa in all wings corresponds with the front or upper margin of 
the wing and need not be designated. Label all veins -and cross 
veins. 

3. Diagrams of Cranefly Wings. Upon the sheet of crane- 
fly wings furnished, mark in pencil the names of the longitudinal 
veins and crossveins. The instructor will assist you in labeling this 
sheet. Begin with a wing which most nearly approaches the struc- 
ture of the hypothetical wing. 



72 

4. Diagrams of Psocid Wings and Fungus Gnat Wings. 
In labeling these two sheets of wing diagrams, assistance will be 
given only on one of the sheets. The third one (to be designated 
by the instructor) must be worked out independently by each student. 

Summary 

1. Which of the cranefly wings on the sheet do you consider most primitive 
or generalized? Which most specialized? Why? 

2. Why is or isn't the flapper of a whale homologous to the wing of a bird? 

3. Are the teeth of a rabbit homologous or analogous to the teeth of a lobster? 
Why? 

Note. When the wing sheets have been corrected and returned to you, take 
the sheets to the laboratory and color subcosta, media and the anal veins red 
and the cross veins blue. For this work refer to the diagrams which you will 
find in the laboratory. These corrected sheets form the basis of a study on 
Phytogeny, Exercise 22, and should be brought to the laboratory at that time. 
(The instructor will give further details). 



EXERCISE 21 

SERIAL HOMOLOGY 

PLASTICITY OF FORM AND PERSISTENCE OF TYPE IN 

MALACOSTRACA 

References. Needham, General Biology pp. 230-236; Calkins, Biology pp. 
166-172. 

Material and Apparatus Needed. Simple microscopes; living and pre- 
served specimens of crayfish, Gammarus, and Asellus and preserved specimens of 
Squilla; Riker mounts of the appendages of the crayfish, squilla and asellus; 
tabulated blanks; dissecting trays, and dissecting instruments. 

Serial homology is homology repeated in a series. The segments of the earth- 
worm back of segment thirty are serially homologous because they are all made 
up of essentially the same structures. 

The body of the crayfish, Gammarus; Asellus and Squilla is made up of a series 
of twenty segments and each of these segments bears a pair of jointed appen- 
dages. These appendages are all built on the same general plan, and although 
they are of different shapes and perform different functions, the parts can all 
be homologized. Thus we find that the appendages are serially homologous. 
The appendages of the abdomen are the simplest in structure and the funda- 
mental parts may be more easily distinguished in them than in the more special- 
ized appendages, such as the legs or the mouth parts. t ^L:i'l^ 

LABORATORY EXERCISE 

i 
1. Crayfish (Cambarus). 

a. Study the living specimen and determine the different uses 
to which the appendages are put. 

b. Study the appendages of a preserved crayfish, referring to 
the Riker mounts for guidance. Begin with the series of appen- 
dages and, for convenience in dissecting, proceed from the pos- 
terior end forward. Remove each appendage of one side in order, 
being very careful to get each one off entire. Place the appen- 
dages on a sheet of paper in their proper order. The twentieth 
segment (telson) does not bear any appendages. The broad 
finlike appendages (uropods) on each side of the telson belong to 
segment 19. The appendages on the abdomen are called swim- 
mer ets. If the specimen you have is a female, the appendages of 
the first abdominal segment are much reduced; if a male, the 
appendages of the first and second abdominal segments are special- 
ized, bent strongly forward under the thorax, and variously forked 
or twisted at the tip. They function in reproduction. 

73 



74 

Before removing the appendages of the thorax, remove the side 
piece (carapace) which covers the gill chamber. This will expose 
the feathery gills. Move the legs backward and forward and note 
that the gills are attached to the basal segments of the legs. Remove 
each leg, with its attached gill, proceeding from the rear. Examine 
each leg and determine whether it is used for defense, grasping or 
walking. In what way do the legs differ in structure ? There yet 
remain three pairs of thoracic appendages. These are the max- 
illipeds (foot jaws). They cover the mouth, being directed forward. 
These maxillipeds assist in manipulating the food. Remove the 
maxillipeds carefully and compare them in structure with the typical 
abdominal appendages already studied. Which of the maxillipeds 
bear gills? The remaining appendages belong to the head. Closely 
following the maxillipeds, and covered by them, are two pairs of 
very thin and delicate maxillae. B e careful to remove them separate- 
ly and entire. In front of the maxillae find the mandibles, a pair 
of hard toothed jaws, each with a small, three-jointed palpus lying 
in a groove on its anterior surface. Remove one of the mandibles. 
On the front of the head are two pairs of feelers, the larger single ones 
the antennae, and the smaller two-forked or double ones the antenn- 
ules. After having removed all the appendages from one side and 
properly arranged them on a sheet of paper compare their structure. 
They are all homologous having been modified from one type of 
structure. 

Record. Upon the sheet, ' 'Table of Malacostracan Appendages. ' ' 
provided, record in the first column the results of your observations. 
For the names of the appendages use the following abbreviations : 
antennae and antennules = ant. cheliped = chp. 
mandibles = md. grasping leg = gr. 1. 

maxillae = mx. walking leg = walk. 1. 

maxillipeds = mxp. swimmer ets = sw. 

2. Gammarus. 

a. Living Specimen. Study the living specimen and note its 
mode of locomotion. 

b. Study the appendages of a preserved specimen, referring to 
the glass slide mounts for help. Note that the body of this animal 
is likewise made up of twenty segments, each of which, except 
the last one, bears a pair of appendages. Study each of the appen- 
dages carefully and see in what way they differ from the appen- 
dages of the crayfish. 



75 

Record. In the second column of the sheet record your observa- 
tions, using the abbreviations given for the crayfish. The appen- 
dages of the last few abdominal segments are used for jumping and 
should be recorded as jumping appendages = jump. ap. 

3. Asellus. 

a. Living Specimen. Examine under the demonstration 
microscope a living Asellus which has been placed on its back. 
The appendages of segments 17 aud 18 have been modified into 
gills and the appendages of segments 16 into a gill cover {opercu- 
lum). Note that the movement of these appendages produces a 
current of water which passes over the gills. Note also the loco- 
motion of an Asellus. They do not swim, but walk or crawl on 
their legs. 

b. Study the appendages of Asellus from the prepared slides. 
Segment 20 has no appendages and segment 19 bears a pair of 
processes, called stylets. 

Record. \ In the third column record your observations of the 
appendages of asellus. 

4. Squilla. Study the preserved specimens and Riker mounts 
of Squilla. Note the similarity of the appendages to the appendages 
of the crayfish. To what appendages are the gills attached? 

Record. In the fourth column record your observations of the 
appendages of Squilla. 

5. Functions of Malacostra can Appendages. Having studied 
and recorded the kinds of appendages found in the four types of 
Malacostraca, fill out the table of "Functions of Appendages" on 
the right half of the sheet. Conclusions should be based, first on 
what you have observed of the uses of the appendage while study- 
ing the living specimens, and second on the inferences which you are 
able to draw from the form and location of the appendages. In 
this table indicate by number the segments which are involved in 
each function. Thus in Cambarus, swimming involves 16-19 in 
the male, and 14-19 in the female, etc. 

Summary 

1. In your own words express the meaning of serial homology. 

2. How do you account for the general resemblance in number of segments 
and form of appendages in the four species? 

3. How do you account for the difference in use of homologous appendages in 
the four forms? 



EXERCISE 22 

PHYLOGENY 

References. Needham, General Biology pp. 236-238. 

Material and Apparatus Needed. The corrected wing sheets which were 
used in the study of Homology. These wing sheets should now have been 
corrected, with the subcosta, media and anal veins marked in red, and the cross 
veins in blue. 

Phylogeny is the study of the ancestral history of organisms. It is the study 
of the race. "A common device for expressing graphically one's conception of 
phylogeny is the so-called 'genealogic tree'." In building up such a tree the 
most primitive or generalized forms are placed near the bottom, the most highly 
specialized ones at the top and the intermediate forms on branches between. 
The phylum Arthropoda represents one branch on the genealogic tree of life. 
The insects represent a smaller branch of this one branch, and so on. 

LABORATORY EXERCISE 

With the corrected wing sheets at hand construct a genealogic 
tree for each of the three series of wings, showing a possible genetic 
relationship (based only upon the data furnished by the venation of 
the figures). Assume that the figure of the hypothetical wing is 
most primitive. 

A. Begin With the Poscid Wings. The instructor will assist in 
the interpretation of the wings of this sheet. Pick out the wing 
which is most primitive (nearest to the hypothetical wing) and place 
the number corresponding to it near the base of the tree. Single 
out in each series the different ways in which the type has been 
modified, and make as many principal branches as there are different 
kinds of divergence. Pick out the most specialized forms for the 
tips of the longest branches. Arrange the others in position in 
accordance with their degrees of divergence, and let the branching 
and length of the twigs represent this. In order to get related forms 
on the same branch study carefully the "behavior" of the different 
veins and cross veins. Note, for instance, that in several of the 
Psocid wings Cu 2 does not bend upwards to meet M but stretches 
out in a nearly straight line to the margin of the wing. These three 
wings undoubtedly belong to the same branch, and the most highly 
specialized one of them to the longest twig of this branch. Compare 
all wings together with respect to each character, the length of Sc, 
the fusion of the tips of M or Cu, the number of cross veins etc. 

76 



77 



B. Cranefly and Fungus-gnat Wings. Each student will 
independently construct a genealogic tree of each of these series of 
wings. In each case briefly state your reasons for placing the wings 
in their respective relationships. 

Summary 

1. Which of the longitudinal veins, in the wings studied, seems to be most 
constant? Which most variable? 

2. In what way is modification in venation, from the hypothetical wing, 
brought about? 

3. Draw a genealogic tree to show the relationship of the following: Amoeba, 
Hydra, earthworm, Parmoecium, frog, sponge, grasshopper and horse. 



EXERCISE 23 
ONTOGENY 

References. Needham, General Biology, pp. 255-261; Ecker, Anatomy of 
the Frog; Holmes, Biology of the Frog. 

Material and Apparatus Needed. The results of the previous laboratory 
studies of the animal types, together with whatever additional available data 
may be at hand; tabulated sheet on which to record results. 

Ontogeny is the development of the individual from the egg to the adult stage. 
"Ontogeny repeats phylogeny," i. e. the development of the individual repeats 
the development of the race. In tracing the development of an individual we 
find that the successive embryonic stages correspond, in general, to the series of 
types of animals from the simplest to the highly developed forms. 

LABORATORY EXERCISE 

A. With the data of the studies on the frog and tadpole at hand, 
enter on the tabulation sheet the ontogenetic changes which are 
found in the development of the frog, under the four headings given. 

B. On the lower half of the sheet enter the data called for under B . 

Summary 

1. What is the biogenetic law? 

2. Distinguish clearly between ontogeny and phylogeny. 

3. Of what evolutionary significance is the correspondence between ontogeny 
and phylogeny? 



78 



EXERCISE 24 
MITOSIS 

References. Needham, General Biology, pp. 289-306; Shull, Principles of 
Animal Biology, pp. 70-83; Sharp, An Introduction to Cytology; Wilson, The 
Cell in Development and Inheritance. 

Material and Apparatus Needed. Compound microscope, prepared 
sections of the onion root tip, hyacinth, or some other tissue which illustrates 
the various phases of mitotic cell division; newly laid eggs of pond snails. 

Mitosis is an indirect method of cell division in plants and animals. It is 
sometimes also called karyokinesis. It is a very complicated process in which 
the nucleus undergoes a series of remarkable changes before the cell actually 
divides into two new cells. Amitosis is a direct method of cell division in which 
the nucleus divides directly into two equal parts. Both methods are found in 
plants and animals but mitotic division is more common and illustrates how hered- 
itary qualities may be transmitted. . Mitosis, in plants and animals, is essen- 
tially alike; the main difference being that in animal cells a centrosome is present, 
while in the higher plants a centrosome has not been found. 

For convenience the process involved in mitotic division, is usually divided 
into four stages: prophase, metaphase, anaphase and telophase. By selecting 
some growing plant or animal tissue, such as the tip of an onion root, hyacinth, 
or the epidermis of a salamander etc, and cutting it into thin sections, all the 
successive stages of division can be seen. 

LABORATORY EXERCISE 

Onion Root Tip. Examine the prepared slide of the onion root 
tip tinder low and high power of the microscope. 

1. Resting Stage. Find a cell on the slide which contains a 
large nucleus surrounded by a nuclear membrane. Within the nu- 
cleus find a small round body, the nucleolus. The granular material 
within the nucleus is called chromatin. The chromatin is deposited 
in a network of very fine and almost invisible threads of a substance, 
called limn. Outisde of the nucleus is the cytoplasm of the cell. 

Make a drawing of the resting cell, at least two inches in diameter, 
showing and labelling the following parts: cell wall, nuclear mem- 
brane, nucleus, nucleolus, chromatin and linin. 

2. Prophase. This is the first stage in the process of mitotic 
division. 

a. Early Prophase. Find a cell in which the chromatin of 
the nucleus has assumed the form of a long, tangled thread. This 
is the spireme. Note that the nuclear membrane and the nu- 
cleolus are still present. 

79 



80 

Make a drawing of the early prophase stage labeling all parts 
shown. 

b. Late Prophase. Now find a cell in which the spireme 
has broken up into a number of short pieces which are called 
chromosomes. The chromosomes migrate to the center of the 
nucleus where they form an equatorial plate, and apparently are 
held in position there by the linin threads which have now formed a 
spindle, called the nuclear spindle. In the late prophase stage the 
nuclear membrane and . nucleolus have usually disappeared. 

Make a- drawing of this stage and label: cell, chromosomes and 
nuclear spindle. 

3. Metaphase. This is the stage in which each chromosome 
splits lengthwise into two identical halves, Thus the chromatin 
material becomes equally divided so that each one of the two re- 
sulting daughter cells will contain just one half of the chromatin 
material of the original cell. 

Find a cell which represents this stage. Make a drawing of this 
phase and label all parts shown. 

4. Anaphase. This is the stage in which the daughter chromo- 
somes move apart toward the ends of the spindle where they will 
form the chromatin material in the nuclei of the daughter cells. 
(This and the following stage is the reverse process of the prophase 
and metaphase). In the late anaphase the spindle fibers become 
thickened in the equatorial region and form the cell plate which later 
becomes part of the cell wall. (This formation of the cell plate is 
found in plants only). 

Find a cell in which the chromosomes have moved to the opposite 
ends of the spindle and make a drawing of this phase, labeling all 
parts shown. 

5. Telophase. This is the final stage in the division, in which 
the nuclei and cells are fully reconstructed. The chromosomes 
have first united in the form of a spireme and then broken up into 
granular chromatin material. The spindle has disappeared and a 
new nuclear membrane and nucleolus have been formed. A wall 
completely surrounds each cell. The cells appear much as the cell 
of the resting stage except that they are only half as big as the mother 
cell from which they arose. 



81 

Find two newly formed cells representing the telophase. Make a 
drawing of this stage and label all parts. 

6. Polar Bodies in Snail's Eggs. The history of the germ 
cell and the origin of the polar bodies should be studied in the text 
before taking up this subject in the laboratory. 

Pond snails, when brought into the laboratory and placed in a 
dish of water with a few lettuce leaves for food, will usually begin 
to lay eggs within a few days. In these eggs one may observe the 
polar bodies. 

Examine the newly laid eggs of snails and note that just outside of 
the egg there are found three (sometimes only two) small round 
bodies. These are the polar bodies. 

Make a drawing of an egg showing the polar bodies. 

Label: egg and polar bodies. 

Summary 

1. What is the significance of mitotic division in plants and animals? 

2. What is the significance of the reduction in the number of chromosomes? 

3. What is parthenogenesis? Where does it occur? 



EXERCISE 25 
THE RELATION BETWEEN FECUNDITY AND NURTURE 

Reference. Needham, General Biology pp. 318-325. 
Material and Apparatus Needed. Button balls (seeds) of Sycamore, 
fern fronds with sporangia, or seeds of the elm, maple or oak. Fishes. 

This study consists, in part, of a field trip to the fish hatchery and students 
should come prepared to make this trip. 

The object of the study is to demonstrate the relation which exists between 
fecundity and nurture. The plants, such as the sycamore tree, do not exercise 
any parental care and therefore they must produce an enormous number of seeds 
in order that the continuation oi the species may be insured. The altricial 
birds produce only a few eggs and their young receive parental care for a long 
period of time. The precocious birds produce many eggs and give no or little 
parental care to their young. Ultimately about the same number of altricial 
and precocious birds reach maturity. The fish, which care for their young, 
produce comparatively few eggs while those which give no care to the young 
produce a much greater number of eggs. 

EXERCISE 

1. Sycamore Tree. Select a large sycamore tree and note 
the button balls (seed balls) . These balls are composed of a number 
of seeds. Count the number of button balls on a large limb. Then 
estimate what proportion this limb bears to the whole tree. In 
this manner determine the number of button balls on the entire 
tree. Now divide a button ball into 6 or 8 equal parts and count 
the number of seeds in one part. By multiplying this number by 
the number of parts into which the button has been broken, the 
entire number of seeds in one button ball is found. Estimating 
that only about 75 percent of the button balls have remained on the 
tree and that the fruiting life of the tree extends over a period of 75 
years, calculate the number of seeds which a sycamore tree may pro- 
duce during its lifetime. 

This method, though crude, will give one a fair idea of the possible 
number of seeds the tree may bear. 

2. Fishes. To appreciate the reduction in numbers which goes 
with a little parental care a comparison will be made on the number 
of eggs which are produced by some nesting fish, such as the stickle- 
back, sunfish, bass or bullhead, with those produced by the pike or 
carp, which scatter their eggs broadcast. 

Since the number of eggs which a fish lays is very large, an esti- 
mate may be made as follows: Place the ripe ovary containing the 

82 



83 

eggs into a graduate in which there is a known quantity of water of 
such volume that when the eggs are placed in it, they are entirely 
submerged. Deduct from the new reading, the quantity of water 
first introduced. The result is the volume of the eggs in the ovary. 
Next measure the diameter of a single egg and then, by means of the 
table on page 84 compute the number. Calculate the number of 
eggs produced by the various species of fishes which are studied. 

Summary 

1. Distinguish clearly between the terms altricial and precocious. 

2. What would be the result if the pike or carp exercised parental care as 
does the stickle-back? 



Table for Finding Number of Fish Eggs of Given Diameter per Liquid Quart. 



Diameter 


Number 


Diameter 


Number 


Diameter 


Number 


Diameter 


Number 


Inch. 




Inch. 




Inch. 




Inch. 




0.300 


2,506 


0.230 


5,562 


0.160 


16,521 


0.090 


92,826 




2,531 




5,635 




16,835 




95,990 




2,557 




5,709 




17,157 




99,297 




2,583 




5,785 




17,487 




102,762 




2,609 




5,862 




17,825 




106,390 


0.295 


2,636 


0.225 


5,941 


0.155 


18,172 


0.085 


110.190 




2,663 




6,021 




18,528 




114,172 




2,690 




6,102 




18,894 • 




118,346 




2,718 




6,185 




19,270 




122,730 




2,746 




6,269 




19,655 




127,333 


0.290 


2,775 


0.220 


6,355 


0.150 


20,050 


0.080 


132,170 




2,804 




6,442 




20,456 




137,251 




2,833 




6,531 




20,874 




142,600 




2,863 




6,622 




21,303 




148,220 




2,893 




6,715 




21,744 




154,155 


0.285 


2,923 


0.215 


6,809 


0.145 


22,197 


0.075 


160,400 




2,954 




6,905 




22,662 




166,995 




2,985 




7,002 




23,140 




173,950 




3,017 




7,102 




23,633 




181,300 




3,050 




7,204 




24,140 




189,070 


0.280 


3,083 


0.210 


7,307 


0.140 


24,661 


0.07C 


197,290 




3,116 




7,412 




25,197 




205,992 




3,150 




7,520 




25,748 




215,204 




3,184 




7,629 




26,316 




224,995 




3,219 




7,741 




26,901 




235,377 


0.275 


3,254 


0.205 


7,855 


0.135 


27,504 


0.065 


246,410 




3,290 




7,971 




28,125 




258,141 




3,326 




8,089 




28,764 




270,631 




3,363 




8,210 




29,422 




283,936 




3,400 




8,333 




30,101 




298,132 


0.270 


3,438 


0.200 


8,459 


0,130 


30.801 


0.060 


313,289 




3,476 




8,587 




31,523 




329,490 




3,515 




8,717 




32,268 




346,828 




3,555 




8,851 




33,036 




365,405 




3,595 




8,987 




33,829 




385,331 


0.265 


3,636 


0.195 


9,126 


0.125 


34,647 


0.055 


406,733 




3,677 




9,268 




35,492 




429,750 




3,719 




9,413 




36,364 




454,539 




3,762 




9,561 




37,265 




481,270 




3,806 




9,712 




38,198 




510,139 


0.260 


3,850 


0.190 


9,866 


0.120 


39,161 


0.050 


541,362 




3,895 




10,023 




40,156 




575,173 




3,940 




10,184 




41,186 




611,893 




3,986 




10,348 




42,251 




651,776 




4,033 




10,516 




43,354 




695.223 


0.255 


4,081 


0.185 


10,688 


0.115 


44,494 


0.045 


742,613 




4,129 




10,863 




45,676 




794,400 




4,178 




11,042 




46,899 




851,128 




4,228 




11,225 




48,166 




913,380 




4,279 




11,412 




49,480 




981,852 


0.250 


4,331 


0.180 


11,603 


0.110 


50,841 


0.040 


1,057,350 




4,383 




11,799 




52,254 




1,140,780 




4,436 




11,999 




53,720 




1,233,250 




4,490 




12,203 




55,239 




1,335,960 




4,545 , 




12,412 




56,817 




1,450.406 


0.245 


4,601 


0.175 


12,627 


0.105 


58,456 


0.035 


1,578,320 




4,658 




12,846 




60,159 




1,721,630 




4,716 




13,069 




61,925 




1,883,020 




4,776 




13,298 




63,766 




2,065,130 




4.835 




13,533 




65,680 




2,271,500 


0.240 


4,895 




13,774 


0.100 


67,670 


0.030 


2,506,310 




4,956 


0.170 


14,020 




69,741 








5,019 




14,272 




71,899 








5,083 




14,529 




74,146 








5,148 




14,793 




76,486 






0.235 


5,214 
5,281 
5,350 
5,419 
5,490 


0.165 


15,064 
15,341 
15,625 
15,916 
16,215 


0.095 


78,927 
81,473 
84,130 
86,904 
89.800 







CONVERSION TABLE 

1 inch = 25.4 millimeters. 1 liter 

1 millimeter = 0.03937 inch. 1 pound 

1 quart = 57.75 cubic inches. 1 kilogram 

1 quart = 0.9464 liter. Fahrenheit 

1 liter = 61.0234 cubic inches. Centigrade 

From von Bayer in Rept. 4th Internat. Fisheries Congress. 

84 



= 1.0567 quarts. 

= 0.4536 kilogram. 

= 2.2046 pounds 

= 9/5 centigrade =*" 32° 

= 5/9 Fahrenheit ± 32 c 



EXERCISE 26 

EXTERNAL METAMORPHOSIS OF INSECTS 

References. Needham, General Biology, pp. 343-347; Comstock, An 
Introduction to Entomology; Comstock, Manual for the Study of Insects. 

Material and Apparatus Needed. Simple microscope, watch glasses, 
forceps, larval and adult forms of about a dozen different insects, tabulation 
sheets for recording the observations. 

Metamorphosis means "change of form." It is the name applied to the 
change of form which takes place in an individual in its development from the 
time when it hatches from the egg until it reaches maturity. It covers the 
postembryonic period of development. In the Vertebrates the transformation 
of the tadpole into a frog may be cited as an example. In the Invertebrates the 
insects illustrate metamorphosis in a marked manner and serve admirably for a 
study of this phenomenon. 

There are two main types of metamorphosis in insects, incomplete and complete. 
Insects which undergo incomplete metamorphosis pass through three develop- 
mental stages, egg, nymph and adult. The nymph, in general, resembles the 
adult form and differs externally chiefly in not having the wings fully developed 
but represented as short wing "pads." The grasshopper illustrates this type of 
metamorphosis. Insects which undergo complete metamorphosis pass through 
four developmental stages, egg, larva, pupa and adult. The larva bears no 
resemblance to the adult form and the wings are developed internally under- 
neath the skin. The pupa is the resting stage in which the larva is "made over" 
into the adult form. The butterfly illustrates this type of metamorphosis. 

LABORATORY EXERCISE 

In this exercise a study will be made of the external differences 
which are found in the young (larva or nymph) and adult forms of a 
number of different species of insects, representing both types of 
metamorphosis . 

Carefully examine each insect with a lens or simple microscope 
and then record the results of your observations upon the tabulation 
sheet furnished. Refer to the footnotes on the sheet for explana- 
tion of the data called for. 

Before handing in your laboratory report, study the questions 
called for in the summary and make notes of any data which will 
be needed in writing up the summary. 

Summary 

1. Divide the insects studied into two groups, those with incomplete meta- 
morphosis and those with complete metamorphosis. 

2. Group those having similar habitats and feeding habits in both young and 
adult stages. 

3. Group those having similar feeding habits but differing in habitats. 

4. Group those having totally different habits in the two stages. 

85 



EXERCISE 27 
INTERNAL METAMORPHOSIS IN INSECTS 

References. Needham, General Biology pp. 347-352; Comstock, An 
Introduction to Entomology pp. 194-205. 

Material and Apparatus Needed. Compound microscope, prepared slides 
of the cross-section of the damselfly nymph and weevil larva, larvae and pupae of 
the willow cone gall midge, sheet with diagrams of the larva and pupa of the gall 
midge, red pencils. 

In the exercise on External Metamorphosis in Insects a study was made of the 
difference in structure in the young and adult forms of a number of insects repre- 
senting complete and incomplete metamorphosis. In this exercise a compara- 
tive study will be made of the internal structures found in the larva (complete 
metamorphosis) of a weevil and the nymph of the damselfly (incomplete meta- 
morphosis). The sections have been made through the region of the thorax so 
as to include the structure of the developing legs and wings. 

LABORATORY EXERCISE 

1. Damselfly Nymph. Under the low power of the microscope 
study the cross section of the damsefly. Arrange the slide so that 
the dorsal part of the section is away from you. 

In the cross section identify the following parts: 

a. Wings. These are located on the dorsal surface and will 
appear as upward projecting lobes. In some of the sections one 
pair of wings may be detached from the body, due to the manner of 
sectioning the specimen. 

b. Legs. These are located on the outer lower, side and will 
be represented as disjointed or disconnected parts. 

c. Digestive tract in the center of the section. Though this is 
typically cylindrical it may appear as a flattened or collapsed 
structure. 

d. Dorsal blood vessel or heart, just above the digestive tract, a 
small, somewhat triangular, tube, cut transversely. 

e. Nerve cord, located below the digestive tract, stained light 
blue and surrounded by reddish-blue muscle tissue. 

f. Air Tubes or Tracheal Trunks. One tube, on each 
side of the median line above the digestive tract, cut transversely. 

g. Muscle. This fills a large part of the body, especially in 
the region of the wings and legs, and appears as bluish stained 
tissue. Where the muscle has been cut transversely it appears as 
closely set reddish-blue dots. 

86 



87 

h. Fat. This is the loose yellowish tissue or cells found scatter- 
ed within the body. 

Make a drawing of the cross section of the damselny to show the 
arrangement of the cell layers, organs etc. The cellular structure 
need not be shown in detail. Label all the parts enumerated above. 
The diameter of the drawing should be at least 4 inches. 

2. Weevil Larva. Study the cross section of the weevil larva. 
In this specimen the wings project or hang downward on the side. 
Arrange the slide so that the dorsal side is away from you. 
Identify the following parts: 

a. Cuticle. This is the outer covering of the body and will 
be represented as a light bluish thin line surrounding the entire 
section. 

b. Wings, on each side a "downward projecting wing bud. 

c. Legs, found in similar location as in the damselny nymph. 

d. Digestive tract, in the center of the body, much smaller than 
in the damselny. 

e. Nerve cord, below the digestive tract, stained light blue 
and surrounded by reddish-blue muscular tissue. 

f . Fat. The main part of the body filled with yellowish stained 
tissue. 

g. Muscle. Bluish tissue, in the region of the wings and legs. 
The dorsal blood vessel is so small that it can not easily be dis- 
tinguished among the fat. 

Make a drawing of the cross section of the weevil larva, showing 
and labeling all parts enumerated above. 

3. Larvae and Pupae of the Gall Midge. This midge 
produces the cone gall of the willow. The larva overwinters within 
the gall and will be found in the central part of the cone gall. The 
blood of this larva is red and as it becomes full grown it will appear 
yellowish white, because it is filled with white opaque fat and this 
covers the red blood within. As the transformation into the pupal 
stage proceeds the fat is used up and so the red color of the blood 
reappears. The progress of the metamorphosis may, therefore, 
be guaged by the extent of the red color; later as the end of the 
pupal period approaches, the black pigmentation of the adult will 
gradually overspread the surface, beginning with the eyes. The 
early pupal stage will therefore be red while the later pupal stage will 
be blackish. 



88 

Upon the sheet of diagrams provided, indicate with black and red 
pencils, the distribution of pigment to indicate the external evidence 
of the internal changes. Show thus the place of beginning and the 
order of progression in fat solution, and later progress in pigmentation. 

Summary 

1. Of what significance is the distribution of fat with reference to the manner 
of metamorphosis in the insect? 

2. What is the advantage of complete metamorphosis to insects? 

3. Give an illustration, other than that studied in the laboratory, of complete 
metamorphosis; — of incomplete metamorphosis. 



EXERCISE 28 

PLANCTON 

References. Needham, General Biology pp. 525-527; Ward & Whipple, 
Fresh Water Biology. 

Material and Apparatus Needed. Compound microscope, glass slides, 
cover glasses, pipette, and a collection of living plancton freshly obtained from 
some nearby lake or pond. 

In all lakes, ponds and streams there exists a population of microscopic plants 
and animals suspended in the open water, or floating or drifting or swimming 
about, collectively known as plancton. It is a vast assemblage of minute, trans- 
parent organisms, the existence of which was not suspected a hundred years 
ago. Being invisible they were unnoticed. Yet they constitute a vast popu- 
lation, well adjusted to its place in the world, self -sufficient, self -maintaining, and 
independent of the life of the land. Both plant and animal forms show many 
adaptations to a life of drifting about in the open waters. Their very minuteness 
greatly favors drifting, but in addition to this they secrete internally bubbles of 
gas or drops of oil, lightening their specific gravity, or they develop long hairs 
and spines which greatly increase superficial area, and surface friction with the 
water. Plancton organisms include of necessity many chlorophyl bearing forms, 
(green, or blue-green or light amber-brown in color): these constitute the pro- 
ducing class. Animal forms are present also in great variety, and constitute, 
as on land, the chief consuming class. 

Material for laboratory study may be obtained by straining a large amount of 
water through a fine silk net in which the organisms are retained, or better, by 
towing a cone-shaped net through the water behind a boat. In this manner a 
large number of organisms collect in the cone of the net from which they are 
transferred to a jar of water. 

LABORATORY EXERCISE 

Mount on a clean glass slide a small drop of the plancton culture, 
put on cover glass and examine under the microscope. By means of 
the figures and description in the "Genera of Plancton Organisms" 
on page 102 identify the plants and animals found. When in doubt, 
ask the instructor. As soon as you identify an organism make a 
drawing of it. 

Examine and make drawings of as many different specimens as 
you can. Hasten slowly. Distinguish carefully. 

On a separate sheet make a table with the following column head- 
ings and list the organisms which you have studied. 

Name, class, color, relative size, relative abundance, consumer or 
producer. 

89 



90 



Summary 



1. Select 5 examples of plancton organisms studied, and state in what way 
each is particularly adapted to its mode of life. 

2. What relation do the different groups of plancton organisms bear to each 
other? 



EXERCISE 29 

WOODLAND PLANT SOCIETY 

References. Needham, General Biology, pp. 368-374; Gray, Manual of 
Botany; Britton & Brown, Illustrated Flora of the Northern States and Canada. 

Material and Apparatus Needed. A wood lot which has not been unduly 
disturbed by "improvements;" tabulation sheet on which to record the observa- 
tions; a pick axe or some other instrument for use in digging up plants. 

To study the adjustment of organisms to their environment we select a wood 
lot which has retained its natural condition as nearly as possible. Here we 
find an assemblage of plants each adjusted in its place, thus effecting a mutual 
adjustment to the environment. This adjustment in place is determined by 
such factors as light, water, food supply, time of fruiting etc. 

LABORATORY EXERCISE 

This study consists of a field trip and students should come pre- 
pared to take a tramp through the woods. 

Upon the tabulation sheet enter the data called for. 

Summary 

Give very briefly such reasons as you can find for the great abundance of the 
dominant forms, for the localization and limitation of the others and for the 
persistence of all in a permanent self-adjusting association. 



91 



EXERCISE 30 

POLLEN PRODUCTION AS AFFECTED BY ITS 
MODE OF DISTRIBUTION 

References. Needham, General Biology, pp. 400-404; Gray, Manual of 
Botany; Britton & Brown, and other works of Botany. 

Material and Apparatus Needed. Compound microscope, glass slides and 
cover glasses, forceps, dissecting needles and flowers of the three types in- 
dicated below: 

I. Wind (1- Tree — oak, hickory, poplar, boxelder or horn 
pollinated \ beam. 

[2. Herb — sedge, grass or meadow rue. 

'3. A large open solitary flower such as trillium or 
may-apple. 

II. Insect 4. An open, loosely clustered flower, such as 
polinnated spring beauty or buttercup. 

5. A highly specialized bilateral flower, such as 
wood betony or sweet pea. 

6. A composite flower, such as the dandelion. 

III. Self (7. Open, chickweed (Stellaria media) or door 
pollinated \ weed (Polygonum). 

[8. Clistogamous, the blue violet. 

All flowers except the violet should be freshly collected specimens 
in which the anthers have not yet begun to shed their pollen. The 
clistogomous flowers of the violet should be collected in the summer 
and may be preserved in formalin or alcohol. With some of the 
smaller flowers it may be found desirable to make glycerin jelly mounts 
of the pollen grains. 

The study of pollen production and its mode of distribution serves 
to illustrate the adjustment of organisms to environment and particu- 
larly adjustment in manner of life. It illustrates the principle 
methods in which the pollen of plants is distributed so that fertilization 
is affected and the continuation of the species may be insured. The 
immediate object of the study is to learn what the ratio is of the 
number of pollen grains to the ovules produced in the different types 
of plants. 

LABORATORY EXERCISE 

Begin this work on a large flower, such as trillium. Place the 
anther on a glass slide and with a sharp scalpel cut it into two equal 
halves. In similar manner subdivide one half until you have only one 
fourth or one eight of the entire anther on the slide. Upon this place 

92 



93 

a drop of water and cover with a cover glass. Gently tap the cover 
glass until the pollen grains separate out. Put under low power of 
the microscope and count the pollen grains present and then multiply 
to get the whole number per anther. Then fill in the data called for 
on the tabulation sheet. 

Small anthers, like those of the dandelion, may be mounted entire 
under a cover glass, and their pollen grains counted at once. Study 
all eight types of flowers furnished and enter the data on the tabulation 
sheet. With perfect flowers the ratio of pollen grains to ovules 
produced will be the same for the whole plant as for the single 
flower, but with monoecius and dioecious species it will be necessary 
to count and estimate for equivalent proportions of the total of male 
and female inflorescens. 

Summary 

1. Does the degree of clustering of the flower aggregation have any effect 
on the amount of pollen produced? 

2. What are the methods of pollination and what is the effect upon the 
amount of pollen produced in each case? 



EXERCISE 31 
READAPTATION OF INSECTS TO AQUATIC LIFE 

References. Needham, General Biology pp. 407-415; Needham & Lloyd, 
Life of Inland Waters pp. 273-280. 

Material and Apparatus Needed. Simple and compound microscopes; 
prepared slides of different types of insect gills; living and preserved larvae of 
dragonfly, damselfly, mayfly, slonefly, caddisfly, and blood worm or blackfly. 

This study illustrates how some insects, which primitively were terrestrial, 
have adapted themselves to aquatic life by the development of various types of 
respiratory gills. Gills are found only in the immature stages (larvae or nymphs). 
All adult insects breathe air directly through open spiracles which lead to the 
tracheal tubes within the body. 

The gills of insect larvae are of two principal types: bloodgills and tracheal 
gills. Blood-gills are cylindric outgrowths of the body into which the blood 
flows. The exchange of gases takes place between the blood inside the gills 
and the water outside. These gills are similar to gills in vertebrates. Tracheal 
gills are cylindric or flattened outgrowths of the body, traversed by fine tracheal 
tubes. The exchange of gases is between the air within the tracheal tubes and 
the water outside. There is a great diversity of form, position, arrangement, 
number and size of tracheal gills in the insects selected for study. 

LABORATORY EXERCISE 

1. Study the following insect larvae and notice in each case the 
form, structure, arrangement etc., of the gills: (1) Midge or Black- 
fly; (2) Dragonfly; (3) Damselfly; (4) Stonefly; (5) Mayfly; (6) 
Caddisworm. Upon the sheet furnished, complete the figures by 
adding the gills in their proper position. 

2. From the prepared slide mounts make drawings of the following 
gill types. 

a. A blood-gill of the midge or blackfly. 

b. An external lamelliform tracheal gill of the damselfly and 
mayfly. 

c. An external tracheal gill of the caddisworm and stonefly. 

d. An internal lamelliform tracheal gill of the dragonfly nymph. 

3. Prepare a table showing comparative development of gills in 
each of the insect larvae studied under the following headings: 
Name; gill type; number; form: on segments: arrangements. 

Summary 

1. How do you distinguish blood gills from tracheal gills? 

2. What biologic principle does this study illustrate? 

94 



EXERCISE 32 

ANIMAL COLORATION 

References. Needham, General Biology pp. 422-433; Folsom, Entomology, 
chapters 5 and 6. 

Material and Apparatus Needed. A number of living and preserved 
animals to illustrate the different types of animal coloration as listed on the 
record sheets. 

The study of animal coloration is used to illustrate the adjustment of organ- 
isms to their environment, and particularly adjustment in bodily characteristics. 
The external colors which most animals possess serve in the main as a protection 
for the individuals themselves. The animal may thus be protected from its 
enemy through the close resemblance of its body to its surroundings, in which 
case the resemblance is spoken of as protective; or the resemblance may be 
aggressive in which case the possessor of the coloration is enabled to approach 
upon its prey unobserved. 

The most common coloration phenomena in animals are; 

1. Resemblance or "camouflage." This, as stated above, may be either 
protective or aggressive. 

2. Flash Colors. These are colors which are ordinarily hidden and ex- 
posed intermittently in flight. They are sometimes spoken of as directive 
coloration. 

3. Warning Coloration. Animals which come under this heading are 
usually possessed of some bad quality which makes them undesirable as food. 

4. Mimicry. This is a superficial resemblance which some animals exhibit 
to other animals, thereby securing concealment, protection, or some other ad- 
vantage. 

LABORATORY EXERCISE 

Upon the record sheets furnished enter the data called for. Re- 
member that in the laboratory it is impossible to exhibit the animals 
in their natural surroundings and it will therefore be necessary to 
try to picture them in your imagination as they occur in their en- 
vironment. 

Summary 

1. Distinguish between mimicry and protective resemblance. 

2. Give one or two examples, other than those studied in the laboratory, of 
animal coloration under each of the four headings. 



95 



EXERCISE 33 

DEMONSTRATION OF THE FUNCTIONS OF SOME OF THE 

PRINCIPAL PARTS OF THE NERVOUS SYSTEM 

OF THE FROG 

References. Needham, General Biology pp. 460-468; Holmes, Biology of 
the Frog. 

Material and Apparatus Needed. Living frogs, dissecting instruments, 
aquarium, weak acetic acid, small camel's hair brush, induction coil and dry cell 
battery, prepared dissections of frogs to show the brain and spinal cord. 

This exercise is largely a demonstration by the instructor. The student will 
take notes and make sketches to illustrate the various steps in the experiment. 
This experiment, though crude, illustrates the functions of the principal parts of 
the nervous system of the frog. Cruel as this exercise may seem it must be noted 
here that the first operation of removing the cerebral hemispheres deprives the 
frog of all consciousness — hence the succeeding operations are not "felt" by the 
animal. 

LABORATORY EXERCISE 

1. The Uninjured Frog. Note its activity, manner of jump- 
ing, swimming, response to such stimuli as the tilting of the support 
on which it rests, etc. The student should first become familiar 
with the living normal frog, so as to be able to judge the changes 
produced in its actions by the loss of parts of the nervous system. 

2. The Frog With the Cerebral Hemispheres Removed. 
The cerebral hemispheres are removed by making a transverse in- 
cision into the skull just back of the tympanic membranes. 

Note that the frog has lost its want of volitional activity. Test 
its power for correlated movement by throwing it into water and 
making it swim; by tilting the object on which it rests; by making 
it jump. Try to determine whether it can see and hear. A frog 
in this condition may be kept alive for weeks or months but the food 
must be placed in its mouth; otherwise the frog would starve even 
if plenty of food were available. Why? 

3. The Frog That has also Lost Its Cerebellum and Mid- 
brain. After removing the cerebellum and mid-brain try the same 
experiments (as under 2), noting especially the effect of this loss upon 
the coordination of its movements. 

4. With the Spinal Cord Severed at its Junction with the 
Medulla. Observe how the severance of the brain from the cord 

96 



97 

has affected the tone of the body as whole. Hang a brainless frog 
up by its head for convenience in manipulation and test its body at 
various points for reflex responses to stimulation of the skin. A 
small brush dipped in dilute acid, or an electric current, may be used 
to touch the skin. 

To demonstrate the correlation mechanism within the nerve 
centers that remain, stimulate one side of the frog in the flank with 
the acid, or electric current, and notice the foot of the same side 
lifted and rubbed against the spot as if to wipe it off. Then stimu- 
late the flank again in like manner, but hold the foot of that side 
by the toes to keep it from repeating the act. After one or more 
attempts to use this foot, the foot of the other side will be lifted and 
swung around to the spot stimulated. This illustrates cross re- 
flexes. 

5. With the Spinal Cord Destroyed. The spinal cord may 
be destroyed by thrusting a wire down the vertebral column and 
twisting it, thus breaking up the reflex arcs. 

After the spinal cord has been destroyed test again for responses 
by stimulating the frog with dilute acid or the electric current. 

6. Stimulation of the Sciatic Nerve. Expose the great 
sciatic nerve which appears as a coarse white thread lying between 
the muscles of the inner side of the thigh. Stimulate this nerve 
directly to produce muscular response. Then trace this nerve to its 
forking at the knee, and stimulate each of its main branches separate- 
ly to see the specifically different responses resulting. 

7. Make a drawing, properly labeled, of the brain and spinal 
cord of the frog and indicate where the cuts were made in the fore- 
going experiments. 

8. Compare the brain of the frog with brain of a higher verte- 
brate, such as the rabbit or pigeon. Make drawings, properly 
labeled, and tell wherein the brains differ. 

Summary 

1. What is a reflex arc? 

2. In what phase of the experiment was it demonstrated? 

3. Give 5 examples of reflex actions in human beings. 

4. Of the examples cited which were reflex from birth, and which have be- 
come so through practice. 



EXERCISE 34 
THE INSTINCTS OF THE TENT CATERPILLER 

References, Needham, General Biology, pp. 527-529; Slingerland and 
Crosby. Manual of Fruit Insects, pp. 112-117. 

Material and Apparatus Needed: Hand lens or simple microscope, 
riker mounts containing all stages of the complete life history of the tent cater- 
pillar, twig or branch of tree showing the egg mass and nest. 

This is a study on instincts. Instinct is an "inherited tendency to perform a 
specific action in a specific way when the appropriate situation occurs." The 
tent caterpillar, in its life cycle, passes through a series of marked changes of form 
and in each it is fully equipped for doing the necessary things in the right manner. 
There is no reasoning or previous experience, its actions are guided entirely by 
nstinct. 



EXERCISE 

A. Field Trip. If convenient observations should first be 
made in the field upon the living insects to note the natural habitat 
of the caterpillars, the location of the egg masses and the location 
and structure of the "tent." 

B. Laboratory Exercise. Study the different stages of the 
tent caterpillar in the riker mounts and the twig which shows the 
position of the egg mass and the nest. 

Make drawings of the following: 

1. Twig showing position of egg mass and nest. 

2. An egg cluster as seen from the side. 

3. A cross-section of an egg mass. 

4. Side-view of the caterpillar. 

5. Pupa and cocoon. 

6. Male and female moth. 

Make a list of all the instincts which the life history of the cater- 
pillar and moth illustrate. 



Summary 

1. Write out the life history of the tent caterpillar. 

2. What type of metamorphosis is illustrated? 

3. What is the economic importance of the tent caterpillar? 

4. How may they be controlled? 

98 



EXERCISE 35 

LEARNING BY TRIAL AND ERROR IN CHICKS 

References. Needham, General Biology pp. 479-484. 

Material and Apparatus Needed. Healthy young chickens, a week to 
ten days old; food and water for the chickens; a labyrinth made on the plan 
shown in figure 4 below; record tabulation sheets. 

This study consists in observations on the details of the method of a chick in 
learning the route through the labyrinth from one end to the other. The chick 
does not learn things by the reasoning method but by repeated haphazard trials 
it stumbles upon the right course. Every time the act is repeated the subse- 
quent preformances become easier until the chick has learned by the trial and 
error method. 



s 


2 


3 


/©',' 


1 




4 





Fig. 4 
Diagram of a simple box labyrinth, s = chicks, f = food, 1, 2, 3, 4 = points of 
record in the passageway. 



LABORATORY EXERCISE 



Not more than eight or ten observers should gather around one 
labyrinth. 

1. Place the chicks as indicated in figure 4, several of 
them around a plate of food in one end of the box, and one chick 
(the subject of the experiment) alone and without food in the other 
end. The group will feed and chirp contentedly, and the other 
one, moved by the sound of their social converse and by his gre- 
garious instincts, will (if not too well fed) try to get to the others. 

99 



100 

Observe in detail his methods. Let one person be time keeper, 
and let the others record impartially all the efforts of the chick. 
Mark the chicken that is to be the first subject of the experi- 
ment in some way (or note its personal characteristics) so that 
the same one may be taken again for repetition of the trial. Re- 
cord all its acts and the time it takes to find the way to its mates. 
Return it to the starting point and record again; and repeat until 
the chicken has made ten trials. Record on the tabulation sheet 
the results of the successive trials. 

2. Repeat with a second and third chicken. 

Summary 

1. What conclusions are you able to draw from this laboratory experiment? 

2. Upon what conditions does this method of learning rest? 



GENERA OF PLANCTON ORGANISMS 

The following pages contain figures and very short descriptions of 
the more common genera of planet on organisms. A number of 
forms, especially green algae, are included which are not truly plane- 
ton organisms but they so commonly occur in ponds and streams 
that it seemed advisable to include them. In order to make identi- 
fication as simple and non-technical as possible for the beginner it 
seems advisable to let the student learn to recognize the different 
forms by comparisons with the figures and the short descriptions 
which are given. For a more complete treatise on the subject, 
with keys, figures and descriptions, the student is referred to Ward 
and Whipple, Fresh Water Biology, and other works. 

In each of the groups an asterisk has been placed before the genera 
which probably will be most commonly encountered. 

The plates are from Johannsen and Lloyd, Genera of Plancton 
Organisms of the Cayuga Lake Basin, and are used with their per- 
mission. 



102 



BLUE-GREEN ALGAE 




oooo 
oooo 
oooo 
oooo 

6 




1, Phormidium. 2, Tetrapedia, 3, Aphanizomenon. 4, Anabaena. 5, Oscillatoria. 6, Mer" 
ismopedia. 7, Rivularia. 8, 9, Microcystis. 10, Ccelosphasrium. 11, Nostoc. 12, Spirulina, 
13, Apanocapsa. 



BLUE-GREEN ALGAE 

The blue-green algae are characterized by a bluish-green color; they are 
either free floating or they live in masses of gelatine; reproduction is by simple 
division. 

1. Phormidium. Many- celled filaments, straight or bent, surrounded by a 
slimy sheath. 

2. Tetrapedia. Cells flat, quadrangular, occurring either singly or in colonies. 

3. Aphanizomenon. Many short, straight, filaments aggregated in bundles, 
so as to form a feathery mass. 

*4. Anabaena. Single filaments, the cells not imbedded in gelatine. 

*5. Oscillatoria. Single filaments, composed of many short cells; living 
specimens often exhibit waving or oscillating movements. 

6. Merismopedia. Spherical or oblong cells arranged in plate-like colonies. 
Often the cells adhere together in groups of fours. 

*7. Rivularia. Many filaments found within a globular gelatinous mass. 
The filaments taper considerably toward one or both ends. 

8. 9. Microcystis. Cells spherical, very small, united in great numbers to 
form small solid colonies. 

10. Coelosphaerium. Spherical or oblong cells, closely arranged to form a 
hollow spherical colony. 

*11. Nostoc. Many twisted or contorted filaments aggregated in a spher- 
ical colony. The filaments are imbedded in gelatine. 

12. Spirulina. Single celled, spiral-shaped filaments. 

13. Aphanocapsa. Many small globose cells scattered within a gelatinous 
mass. 



103 



GREEN ALGAE 




1, 2 Pediastrum. 3, Kirchneriella. 4, Dictyosphasrium. 5, Characium. 6, Bulbochsete. 
7, Selenastrum. 8, 9, Coelastrum. 10, Botryococcus. 11, 12, Ankistrodesmus. 13, Richteriella. 
14, Scenedesmus. 15, Ophiocytium. 16, Sorastrum. 17, Spirogyra. 18, 19, Mougeotia. 20, 
Zygnema. 21, Tetraspora, 22, 23, Pleurococcus. 24, Cladophora. 25, Hydrodictyon. 26, 
Crucigenia. 27, Chaetophora. 28, Microspora. 29, Ulothrix. 30, Oedogonium. 31. Tri- 
bonema. 32, Draparnaldia. 

104 



GREEN ALGAE 

The green algae are characterized by the green color. They are either uni- 
cellular, clustered, unbranched filamentous or branched filamentous. 

I, 2. Pediastrum. Cells composed of a single layer, forming a plate, whose 
marginal cells possess one or two pointed projections. 

3. Kirchneriella. Crescent-shaped cells occurring in clusters. 

4. Dictyosphaerium. Spherical or oblong cells imbedded in gelatine. 

5. Characium. Single cells attached to some object; shape variable. 

6. Bulbochaete. Branched filamentous plant ; the end cells, and of ten others, 
bearing long colorless hair-like projections which are swollen at the base. 

7. Selenastrum. Small, crescent-shaped cells without pyrenoids. 

8. 9. Coelastrum. Spherical cells arranged in clusters. 

10. Botryococcus. Cells in grape-like clusters, imbedded in gelatine. 

II, 12. Ankistrodesmus. Single or loosely clustered cells, needlelike, often 
variously curved. 

13. Richteriella. Small cells occurring in colonies of four, eight, sixteen or 
more cells, the outer cells bearing long bristles. 

*14. Scenedesmus. Oval or pointed cells, usually occurring in groups of 
four, placed side by side, the end cells often with spines. 

15. Ophiocytium. Single cells, variously shaped, end susually with spine. 

16. Sorastrum. Cells kidney or heart shaped, clustered together in a solid 
mass, the cells bearing short spines. 

*17. Spirogyra. Long filaments composed of many elongate cells which 
contain one, two or more spiral chloroplasts. 

*18, 19. Mougeotia. Long filaments composed of many elongate cells; 
chloroplast an axial plate, with several pyrenoids. 

*20. Zygnema. Long filaments composed of many elongate cells; chloro- 
plasts consist of two radiating or star-shaped bodies for each cell. 

21. Tetraspora. Very small cells arranged in fours, imbedded in gelatin. 

*22, 23. Pleurococcus. Small spherical cells, single or in groups, when grouped 
together the cells are somewhat angulate. Occurs on bark of trees, bricks etc. 

*24. Cladophora. Plants large, branched, cells with many pyrenoids. 

25. Hydrodictyon. Elongate cells joined together so as to form a coarse net. 

26. Crucigenia. Very small, spherical or elongated cells grouped in fours, 
forming a flat plate of 16 or more cells. 

27. Chaetophora. Fine branched filaments imbedded in a gelatinous sub- 
stance and usually ending in a colorless bristle. Much smaller than Cladophora. 

28. Microspora. Filaments composed of short cells. Chromatophore 
granular or netted, without pyrenoids. 

*29. Ulothrix. Filaments composed of cells which are hardly longer than 
wide, chromatophore forming a parietal band with one or more pyrenoids. 

*30. Oedogonium. Filaments composed of long cells, chromatophore with 
several pyrenoids; membranes often with transverse striations at end of a cell. 

31. Tribonema. Unbranched light green filaments, two or more parietal 
chromatophores, no pyrenoids. 

32. Draparnaldia. Main filaments large, bearing lateral tufts of finer branches. 
Terminal cells usually ending in a long hair. 

105 



DESMIDIACEAE 




1, Gonatozygon. 2, Spirotaenia, 3, 4, Docidium. 5, 6,7, 8, Closterium. 9, Desmidium. 
10, Mesotaenium. 12, Netrium. 13, Staurastrum (end view). 14, Staurastrum (side view) 
15, Micrasterias. 16, Genicularia. 17, Penium. 18, Micrasterias. 19, Tetmemorus. 20, 
Pleurotaenium. 21, 22, Cosmarium. 23, Penium. 24, Euastrum. 25, Cylindrocystis. 26, 
Euastrum. 



106 



DESMIDIACEAE 

The desmids are green, unicellular plants, sometimes united into filaments; 
cells made up of two symmetrical halves; chromatophore contains one or more 
pyrenoids. 

1. Gonatozygon. Long cells covered with minute spines; chromatophore 
a central plate in which occur the pyrenoids. 

2. Spirotaenia. Cells oblong, ends rounded, containing one or more spiral 
chromat ophores . 

3. 4. Docidium. Elongate cylindrical cells constricted in the middle; chro- 
matophores are longitudinal radial plates. 

*5, 6, 7, 8. Closterium. Crescent-shaped cells, tapering toward each ex- 
tremity; two chromatophores in each cell; at each end a large vacuole with 
moving granules. 

9. Desmidium. Short cells united to form long twisted filaments; each 
cell constricted in the middle; end view of cell triangular or quadrangular. 

10. Mesotaenium. Very small oblong oval cells; chromatophore a single 
axial plate containing one or more pyrenoids. 

12. Netrium. Oblong cells; two radial flat chromatophores with ridged or 
scalloped margins. 

13, 14. Staurastrum. End view of cells triangular, quadrangular, or radiate; 
side view shaped somewhat like an hour-glass. 

15. Micrasterias. Large disc-shaped cells, deeply constricted in the middle, 
each half of the cell again divided in 3 or 5 lobes, the tips usually bearing spines. 

16. Genicularia. Elongate cylindrical cells covered with fine spines; chro- 
matophores consisting of several parietal spiral bands. 

17. Penium. Elongate cells with rounded or truncate ends, sometimes 
slightly constricted in the middle ; a large pyrenoid in each half of the cell around 
which the chromatophores are radially placed. 

18. Same as 15. 

19. Tetmemorus. Elongate cylindrical cells with a shallow constriction 
in the middle and a narrow incision at each end; a single axial chromatophore 
with a single row of pyrenoids. 

20. Pleurotaenium. Elongate cylindrical cells, swollen before the middle 
constriction; chromatophore a radial plate with a row of pyrenoids. 

*21, 22. Cosmarium. Circular or elliptical compressed cells with a narrow, 
deep middle constriction; each half with a chromatophore which radiates from 
one or more pyrenoids. 

23. Same as 17. 

24. Euastrum. Compressed oblong or elliptical cells with a deep middle 
incision and variously undulating or incised margins; chromatophore axial; 
pyrenoid large. 

25. Cylindrocystis. Oblong cells with rounded ends; two star-shaped chro- 
matophores, radiating from a central pyrenoid. 

26. Same as 24. 

107 



DIATOMS 




39 ^40 



1, 2, 3, 4, Melosira. 5. Stephanodiscus. 6, 7, Eunotia. 8, Stephanodiscus. 9, 10, Cyclotella. 
11, Meridion. 12, 13, 14, Diatoma. 15, Fragilaria. 16, Stauroneis. 17, Cocconeis. 18, 
Frustulia. 19, 20, Nitzchia. 21, 22, Synedra. 23, Pleurosigma. 24, 25, 26, 27, Navicula. 
28, Tabellaria. 29, 30, Gomphonema, 31, 32, Campylodiscus. 33, Cymbella. 34, Pinnularia. 
35, Epithemia. 36, Tabellaria. 37, Asterionella, 38, Surirella. 39, 40, Achnanthidium. 41, 
Amphora. 

108 



BACILLARIACEAE (DIATOMS) 

Yellowish colored unicellular plants, sometimes united in chains; membrane 
silicified, with minute cross stnations or other definite markings. Cells com- 
posed of two parts or valves, the side where the edges of the valves overlap i& 
called the girdle side and the outer surface the valve side. 

I, 2, 3, 4. Melosira. Short discoid cells, circular in crosssection, united into 
filaments; entire valve uniformly marked. 

5, 8. Stephanodiscus. Cells single, valves circular, with raidal rows of dots ; 
around margin a circle of spines of varying lengths; ends of girdle view wavy. 

6, 7. Eunotia. Single cell, more or less curved, with transverse punctate- 
striations, median line (raphe) absent, ends with nodules. 

9, 10. Cyclotella. Single cells, disc-shaped, without spines; valves circular,, 
with a smooth or punctate central area and radiating striations on the outer 
margin; girdle view with wavy ends. 

II. Meridion. Wedge-shaped cells united to form fan-shaped or circular 
bands; valves transversely striate. 

*12, 13, 14. Diatoma. Cells rectangular in girdle view, oblong oval in valve 
view, transversely seriate; cells mostly attached in zig-zag chains. 

*15. Fragilaria. Cells long and slender, valve side wider in middle and at- 
tenuate toward the ends, without transverse ribs; cells united into long ribbons.. 

16. Stauroneis. Single cells, lance-shaped, valve side with broad central nodule 
which extends to near margin of valves ; cross striations of fine dots. 

17. Cocconeis. Valve view of cells oval, raphe straight, middle nodule- 
present but no end nodules. 

18. Frustulia. Similar to Stauroneis, but the central nodule not so broad.. 

19. 20. Nitzchia. Long slender cells, rachis lateral, with a keel at one edge,, 
cells rhomb oidal in cross section. 

*21, 22. Synedra. Cells single, very slender, often attached at one end',, 
forming fan-like stalked clusters. 

23. Pleurosigma. Single cells, S-shaped, central and end nodules present. 

*24, 25, 26, 27. Navicula. Cells more or less lance-shaped, central nodule 
small, cross striations composed of find dots. 

*28, 36 Tabellaria. Girdle view of cells rectangular, with two or more longitu- 
dinal lines from the end toward the center, valve view slender, thickened in the 
middle and at the ends; mostly united into zig-zag chains. 

*29, 30. Gomphonema. Single cells, girdle view wedge-shaped, valve view 
with undulating edges. 

31, 32. Campylodiscus. Single cells, large, saddle-shaped in valve view. 

33. Cymbella. Valve view asymmetrical, girdle view oval or elliptical. 

34. Pinnularia. Oblong cells with end nodules, turned toward one side. 

35. Epithemia. Single lopsided cells, transverse markings coarse and con- 
verging toward the middle. 

*37. Asterionella. Linear cells, enlarged at both ends, united at one end to 
form a wheel or star. 

38. Surirella. Large single cells with looped striations. 

39, 40. Achnanthidium. Single cells with a swelling in middle and ends. 
41. Amphora. Single cells, valve view convex, girdle view elongate ovaL 

109 



FLAGELLATA 




1, Carteria. 2, Sphaerella. 3, Volvox. 4, Chlamydomonas. 5, Dinobryon. 6, Euglena. 
7, Eudorina. 8, Eudorina (young colony). 9, Uroglena. 10, Gonium. 11, Phacus. 12, 
Mallomonas. 13, Pandorina, 14, Uvella. 15, Synura. 16, Pandorina. 17, Ceratium. 18, 
Peridinium. 



110 



FLAGELLATA 

The Flagellates are characterized by the presence of one or more long, flexible, 
whip-like processes (flagella) commonly occurring at one end of the body. They 
are either unicellular or colonial. 

1. Carteria. Nearly spherical single cells bearing four flagella. 

2. Sphaerella. Elliptical single cells bearing two flagella; the membrane is 
widely separated from the chromatophore but connected to it by fine proto- 
plasmic strands. 

*3. Volvox. A large number of small cells united into a large spherical 
colony; each cell bearing two short flagella or cilia. 

*4. Chlamydomonas. Single elliptical or spherical cells bearing two flagella; 
chromatophore single, hollow, parietal. 

5. Dinobryon. Beaker-shaped cells united into dichotymously branched 
colonies ; cells bearing one long . and one short flagellum. 

*6. Euglena. Spindle-shaped single cells, usually green, bearing one flag- 
ellum; a reddish eye-spot at base of flagellum. 

*7. Eudorina. Spherical colonies of eight, sixteen or thirty-two cells evenly 
distributed near the surface of the gelatinous mass; cells bearing two flagella. 

8. Eudorina. Young colony. 

9. Uroglena. Very many small cells united into a spherical, gelatinous 
colony; cells bearing two unequal flagella or cilia. 

10. Gonium. Four to sixteen spherical cells united into a plate-like colony; 
each cell with two flagella. 

11. Phacus. Round to pear-shaped single cells with a longitudinally striated 
surface, a single flagellum present; cells bearing a caudal spine or process. 

12. Mallomonas. Single elongate cells with amber colored chromatophores, 
and a shell of overlapping plates bearing long spines; a single flagellum present. 

13. Pandorina. Eight or sixteen slightly elongate cells closely packed to- 
gether within a gelatinous mass; cells bearing two flagella. 

14. Uvella. Four or five elongate cells, each with two chromatophores and 
two flagella. 

*15. Synura. Many elongate cells held loosely together, each with a thin 
membrane which often is spiny; two unequal flagella present. 

16. Pandorina. Same as 13, single colony enlarged. 

*17. Ceratium. A single cell inclosed in a membranous shell with long spine- 
like processes; a single flagellum present. 

18. Peridinium. A single cell enclosed in a membranous polygonal shell 
without spine-like processes. 



Ill 



CRUSTACEA 




1, Daphnia. 2, Sida. 3, Nauplius. 4, Camptocerus. 5, Simocephalus. 6, Ceriodaphnia. 
7, Eurycerus. 8, Acroperus. 9, Macrothrix. 10, Chydorus. 11, Bosmina. 12, Diaphanosoma. 
13, Polyphemus. 14, Alonella. 15, Leptodora. 16, Diaptomus. 17, Limnocalanus. 18, 
Cypridopsis. 19, Canthocamptus. 20, Cyclops. 21, Eubranchipus. 

112 



CRUSTACEA 

CLAODOCERA, COPEPODA, OSTRAEODA AND PHYLOPODA 

*1. Daphnia. Upper branch of antenna four-segmented, lower branch three- 
segmented; no tranvserse suture on neck; shell with polygonal marks and with 
a posterior spine. 

2. Sida. Upper branch of antenna three-segmented, with many setae, 
lower branch two-segmented; a transverse suture on neck. 

*3. Nauplius. An immatiure stage of Cyclops etc, bearing 3 pairs of appen- 
dages. 

*4. Camptocems. Antennae short; a crest or keel on head and back; post- 
abdomen very long and slender. 

5. Simocephalus. Two pairs of long antennae; shells somewhat quadrate, 
marked with transverse lines. 

6. Ceriodaphnia. Size small, head small, eyes larger; antennae long. 

7. Eurycerus. Size large; post-abdomen very large, with more than 100 
saw-like teeth on dorsal margin. 

8. Acroperus. A crest on head and back; shells obliquely striated. 

9. Macrothrix. Crest on dorsum; antennae long; shells with long movable 
spines on ventral margin. 

10. Chydorus. Body nearly spherical; antennae short and thick; post- 
abdomen short. 

*11. Bosminia. Antennules long and fixed to head so as to suggest a long 
beak; shells truncate behind, the lower angle with a spine. 

12. Diaphanosoma. Antennae very large, about as long as body, upper 
branch three-segmented, lower branch two-segmented. 

13. Polyphemus. Body and feet not covered by shell; four pairs of feet, 
head large; a long caudal process (on ventral side of body). 

14. Alonella. Rostrum long, slender, recurved; shells striated or reticulated, 
truncate behind. 

15. Leptodora. Size very large; body and feet not covered by a shell; six 
pairs of feet; antennae very large; a dorsal brood sac. 

*16. Diaptomus. Outer portion (endopodites) of first swimming feet com- 
posed of two segments, of third and fourth swimming feet of three segments; 
antennae as long as body; posterior body region short; tails (furca) short. 

17. Limnocalarus. Outer portion (endopodites) of all swimming feet com- 
posed of three segments; antennae as long as body; posterior body region long; 
tails (furca) long. 

18. Cypridopsis. Body completely enclosed in a bivalver shell which is 
marked dorsally and laterally with three dark bands. 

*19. Canthocamptus. Antennae short, of eight segments; last abdominal 
segment usually with spine-like processes. 

*20. Cyclops. Antennae shorter than cephalothorax, with not more than 
seventeen segments; female with two egg sacs. 

*21. Eubranchipus. (Fairy shrimp). Elongate body not covered by a 
shell, with eleven pairs of legs. 

113 



ROTIFERA 




1, Philodina. 2, 3, Rotifer. 4, Adineta. 5, Floscularia. 6, Stephanoceros. 7, Apsilus. 
8, Melicerta. 9, Conochilus. 10, Ramate jaws. 11, Malleo-ramate jaws. 12, Microcodon. 
13, Asplanchna. 14, 15 Synchaeta. 16, Triarthra. 17, Hydatina. 18, Polyarthra. 19, 
Diglena. 20, Diurella. 21, Rattulus. 22, Dinocharis, 23, 24, Salpina. 25, Euchlanis. 26, 
Monostyla. 27, Colurus. 28, 29, Pterodina. 30, Brachionus. 31, Malleate jaws. 32, Noteus. 
33, 34, Notholca. 35, 36, Anuraea. 37, Plcesoma. 38, Gastropus. 39, Forcipate jaws. 40, 
Anapus. 41, Pedalion. 

114 



ROTIFERA 

The rotifers are characterized by the ciliated area at or near the anterior end of 
the body. These cilia serve as locomotory organs or to bring food to the mouth. 

*1. Philodina. Two wheel-like discs of cilia (corona); two eyes in the neck, 
directly over the brain. 

*2, 3. Rotifer. Two discs of cilia; two eyes in dorsal proboscis. 

4. Adineta. Corona a flat disc with cilia on the ventral side. 

5. Floscularia. Corona lobed; cilia not in whorls, scattered, or in groups. 

6. Stephanocerus. Corona drawn into 5 long pointed arms or spines which 
bear short cilia. 

7. Apsilus. Short sac-like body; corona a large sac without cilia. 

8. Melicerta. Corona with four lobes; living in tubes, attached. 

9. Conochilus. Corona flat; free swimming clusters or colonies. 

12. Microcodon. Corona somewhat heart-shaped; body ending in a long 
slender foot. 

*13. Asplanchna. Body sac-like, without foot; intestine ending blindly. 

*14, 15. Synchaeta. Corona as broad as broadest part of body, with 2 or 4 
long bristles; at the sides of the corona two large ciliated lobes (auricles) which 
may be retracted. 

16. Triarthra. Body with three long spine-like appendages. 

17. Hydatina. Body ending in two short toes; corona as broad as body, 
composed of a double wreath of cilia. 

18. Polyarthra. Body with 12 blade-shaped appendages, with serrate edges, 
in four groups. 

19. Diglena. Body slender; two toes; corona narrower than head; two eyes. 

20. Diurella. Body quite short, ending in two toes. 
*21. Rattulus. Body elongate, ending in one long toe. 

22. Dinocharis. Head retractile; foot bearing two spines dorsally; foot 
and toes together nearly or quite twice as long as the body. 

23, 24. Salpina. Armor with spines either anteriorly or posteriorly, or both. 

25. Euchlanis. Armor composed of two plates; foot pointed, bearing two 
long toes. 

26. Monostyla. Body armored, with one long rod-shaped toe. 

27. Colurus. Head bearing an arched shield, in side view appearing like a 
hook; foot ending in two short toes. 

28. 29. Pterodina. Corona surrounded by two wreaths of cilia; foot long, 
ringed and ending in a bunch of cilia. 

30. Brachionus. Body armored; spines or teeth in front; foot ending in 
two short toes. 

32. Noteus. Body stout, armed with spines; foot three-jointed; two toes. 

115 



116 

*33, 34. Notholca. Armored, anteriorly with 6 spines, posteriorly ending in 
a long slender spine or else ending in a blunt projection; dorsum of armor with 
longitudinal stria tions. 

*35, 36. Anuraea. Armored, anteriorly with 6 spines, posteriorly ending in 
one or two spines; dorsum of armor marked of! into polygonal areas. 

37. Ploesoma. Armor marked with grooves; foot with two short toes. 

*38. Gastropus. Armor flask-shaped; small foot projecting from ventral 
surface; foot ringed, ending in one or two toes. 

40. Anapus. Armored; head with long finger-like processes; foot absent. 

41. Pedalion. Unarm ored; with six branching, limb-like appendages. 






) 







EXERCISE 2 
OBSERVATIONS ON COMMON INSECT-GALLS 



Cornrnon name of 


Part of P ant Position on 
Affected 2 that part 3 




THE GALL 




THE GALL-MAKER 




Other tenants 10 of the Gall 
and Misc. Remarks 


Plant and Gall 1 


Type 4 


Aggregation 5 Special Features 8 


Name 7 


Greganous Sta g e Found 8 


Mouth Parts 9 


























































































































W^ : 
















































































1 
























































1 







tine ?horizontallv bovine iaws^r/err na A * v ara ¥S re if £ i SU - rfa . ce ' ^Pellants against foraging animals, exit passages for gall makers, etc. 
raw nonzontaiiy moving jaws, p.ercing and sucking, if the beak is jointed: rasping and sucking, if it has mouth hooks. "Parasites, hyperparasites. and guests 



'Upper or lower surface, midrib or membrane or margin or stalk of leaf, axial or lateral in stem and root. etc. 4 See table on page > 13. 
ace. renellante aaninet. tnraaina animals, exit raraopc fn-r «oli ^iqWc <>+r- 'Consult key on pages 14 and IS- i^arva, pupd. ur «*"« • 



6 Solitary clustered 
'Biting, if it has dis- 



EXERCISE 12] 




■ay 



EXERCISE 17 




It 



EXERCISE 20 

DIPTERA-TIPULID.E (CRANEFLIES) 













II 



V - 



-> , -1 



i if 






EXERCISE 20 

DIPTERA (VARIOUS FAMILIES OF FLIES) 











EXERCISE 20 

PSOCIDiE (BOOKLICE) 



5 



». ^= 





7 




8 




io 



ii 



(. 



EXERCISE 20 

diptera-mycetphilim: (FUNGUS GNATS) 





Seg. 



10 



11 



12 



13 

u 

15 
16 



Exercise No. 21 



TABLE OF MALACOSTRACAN APPENDAGES 



KINDS OF APPENDAGES 



in Cambarus 



in Gammarus 



md 



mxp 



in Asellus 



in Squilla 



FUNCTIONS OF APPENDAGES 



Cambarus 



Gammarus 



Asellus 



ft 



O 



'E- ° 
> o 






Ph 



17 
18 



19 



20 



gill 



gill 



Squilla 



Bracket together the segments that are consolidated upon the dorsal side. 
When different in the two sexes divide the space with a diagonal line and write char- 
acters of mate and female in separately. 



table 



Specify function. Indicate segments by number only (/ to 20), as in preceding 
lie. 
Specify characters of male and female separately, where they differ. 



- - 

Iff— — — MWBBSBBHB^^^^^^^^^B 



EXERCISE 22 

ONTOGENY 



A. Comparison of the tadpole stages of the frog with the adult. 

In the following table, note on the dotted line by letter (see list below) the characters indicative of 
the group. 

I. Organs and parts peculiar to the young tadpole stage and wanting in the adult. 



II. 


Organs 


anc 


parts functional in 


the young 


tadpole 


stag 


s and vestigial in 


the adult. 


III. 


Organs 


and 


parts developed in 


both but better in 


the adult stage. 




IV. 


Organs 


and 


parts rudimentary 


or absent in 


the young, 


functional only in 


i the adult. 



a Notochord 

b Sucker pits 

c Lips with teeth 

d Horny teeth in jaws 

e Mucous glands of skin 

/ True teeth in upper jaw 

g Eustachian tube 

h Tympanum 

* Pronephric duct 

j Spiral intestine 

k Fin 

/ Kidneys 

m Two chambered heart 



n Liver 

o Ossified skeleton 

p Gills 

q Cartilaginous skeleton 

r Lungs 

j Sex organs 

t Vocal organs 

u Tail 

v Four aortic arches 

w Heart 

x Eye 

y Tongue 

z Sensory cells in lateral line 



B. In parallel columns compare the following embryonic stages of the frog with the adult form of animals 
lower in the series (i. e.) with protozoa, coelenterates, worms, etc. 



Lower Fobms 



Frog 





One-celled egg 




Eight-cell stage 




Sixteen cell stage 


• 


Thirty-two cell stage 




Morula stage 




Blastula stage 




Gastrula stage 




Young embryo 



; - 



Exercise 26 



EXTERNAL METAMORPHOSIS IN INSECTS 



Name and 


LARVA OR NYMPH ; 


ADULT 


Order 


Ratios 1 


Mouth 
Parts 2 


Wings 3 


Legs 4 


Peculiar 
Parts 6 


Lives 
Where 


Eats 
What 


Ratios 1 


Mouth 
Parts 2 


Legs 4 


Peculiar 
Parts 6 


Lives 
Where 


Eats 
What 


Grasshopper 
Orthoptera 












Meadows 


' Herbivorous 











Meadows 


Herbivorous 


Stone fly 
Plecoptera 












Aquatic 


Mainly 
Carnivorous 








Aerial 


Most eat 
nothing 


May fly 
Ephemerida 












Aquatic 


Herbivorous 










Aerial 


Nothing 


Damsel fly 
Odonata 












Aquatic 


Carnivorous 










Aerial 


Carnivorous 


Dragon fly 
Odonata 












Aquatic 


Carnivorous 










Aerial 


Carnivorous 


Water bug 
Hemiptera 












Aquatic 


Carnivorous 










Aquatic 


Carnivorous 


Cadis fly 
Trichoptera 












Aquatic 


Herbivorous 










Aerial 


Nothing 


Butterfly 
Lepidoptera 












Upon its 
host 
plant 


Herbivorous 










Aerial 


Nectar 
Some do not 
feed 


May beetle 
Coleoptera 












In the 
soil 


Roots 










In trees 


Herbivorous 


Weevil 
Coleoptera 




























Crane fly 
Diptera 












In earth 

or 
Aquatic 


Herbivorous 










Aerial 


Nothing 


Fly 
Diptera 
























Aerial 


Organic 
solutions 



•Relative lengths of head, thorax and abdomen expressed in the ratios 
1 : * : y; the head being taken as 1. 
•Adapted for biting, sucking, or atrophied. 



'Externally or internally developing. 

•Relative development. 

'Found in this larva (or adult) only. 



J 



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• . ; 



EXERCISE 27 



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&07 



* 



EXERCISE 29 



WOODLAND PLANT SOCIETY 



A study in the local and seasonal adjustment of the commoner plants of the Renwick Woods, Ithaca, N. Y. 



Group 1 — Trees 
i. Elm 

2. Maple 

3. Butternut . . 

4. Swamp Oak . 
5- Ash 

6. Sycamore . . 

7. Willow 



9- 



Group 2 — Shrubs 

1 . Spice-bush . . 

2. Elder 

3. Raspberry. . 

4. Currant .... 

5. Viburnum . . 

6. Dogwood. . . 
7 



Height 
in Feet 



Group 3 — Vines 

1. Wild Grape. . . . 

2. Poison ivy 

3. Virginia creeper . 

4. Moonseed 



Checking List; 

Group 4. Tall late herbs 
spreading by 

underground Height 

branches in in. 



1. Aster 

2. Goldenrod 

3. Sunflower 

4. Polygonum .... 

5. Mint (Blephila) 

6. Wood nettle . . . 

7. Sensitive fern . . 



Group 5 — Rosette-forming tall 
herbs 
1. Meadowrue 



Buttercup , 
Geum .... 
Dock 



Group 6 

1. Violet 

2. Ground ivy . . 

3. Moneywort. . . 

4. Forgef-me-not 



Ground-cover creep- 
ing herbs 



Height 
in Feet 



Climbing by 
means of 



Clematis . . . 
Nightshade 
bittersweet , 



Group 7.— Coarse monocots 

with deep Height 

root stalks in in. 

1 . Skunk cabbage 

2. Veratrum 

Group 8. — Slender bulbous 
monocots 

1. Onion 

2. Adder's tongue 

Group 9. — Bulbous crucifers 

1. Bitter cress 

2. Pepperroot 



Group 10. — Annual herbs 

1 . Touch-me-not 

2. Giant ragweed I 



Group 11. — Biennial herbs 

1 . Cow parsnip 

3. Poison hemlock 



Group 12. — Miscellaneous 

1. Stinging nettle 

2. Bedstraw I 

3. Grasses 

4. Sedges |- 

5. Mosses I 

6. Fungi I 



Work Program 

Learn to recognize poison ivy, and then avoid it, unless you are immune. 



II. In the checking list before the name place a: — 

* to indicate those that are vernal plants — those whose vegetative 

activity is at its height in early spring, 
t to indicate those found chiefly in the openings of the forest cover — 

those that require most sun light. 
w to indicate those found in the lower places, nearest the water. 
I to indicate those woody plants that are commonly found rooting 

in fallen logs. 

III. I; Make a general diagram of a vertical section of the woods (including 

one low wet spot) showing stratification of crowns at four levels, 
and of roots in the soil below. Indicate height and depth of strata 
and name on the diagram two of the dominant plants of each 
stratum. 

IV. Make simple diagrams to indicate: — ■ 

1. The underground spread and copse-forming habit of elder or 

viburnum. 

2. The spread of the red raspberry by means of stolons. 

3. The growth habit and asexual mode of increase in one repre- 

sentative each of groups 4, 6 and 9. 

4. The form of one representative each of groups 5, 7, 8 and 10. 

In all these draw a line at the soil level, and indicate height 
and depth. 



c 



- e ir 



Exercise 30 



POLLEN PRODUCTION 



Name 


Sex 1 


Form of 
flower cluster 2 


No. sta- 
mens per 
flower 


No. pis- 
tils per 
flower 


No. pollen 
grains per 
stamen 


No. ov- 
ules 3 per 
carpel 


Ratio of pollen 
grains 4 to ovules. 


1 
















2 
















3 
















4 
















5 
















6 
















7 
















8 
















9 
















10 
















11 
















12 
















13 
















14 

















1 ^dm the r^t' y^, isexual; 2 ' catki n. panicle, loose cluster, head, solitary etc. 3. May be obtained from some work on Systematic Botany; 4. Express- 



?! 



7 



3 






x 







EXERCISE 31 



III. Illustrations of Flash Colors. 










Name 


Color 


Exposed to view 

HOW WHEN- 


FOLDED AWAY 
HOW 


POSSIBLE USE 


Flicker 












Junco 












Roadside grasshopper 












Underwing moth 













IV. Illustrations of Mimicry. 



Name 


Coloration 


Mimicks What 


Whose Defense 

IS WHAT 


Viceroy butterfly 








Syrphus fly 









3 



C 



; 



EXERCISE 31 



Examples from the local Fauna of the principal types of Animal Coloration 

I. Illustrations of Resemblance. 



Name 


Coloration 1 


Type 2 


Details of Resemblance 


Sandpiper 








Backswimmer 








Frog 








Plover 




- 




Least Bittern 








Treehopper 








Leaf insect 








Deadleaf butterfly 








Katydid 








Walking stick 








Water flea 








I. Protective or aggressive 2. General or specific 


II. Illustrations of Warning Coloration. 


Name 


Colors 


Pattern 


Disagreeable Quality 
Advertised 


Bumblebee 








Ant 








Skunk 








Hornet 








Potato Beetle 








Monarch butterfly 








Bee 








Owl beetle 









MAYFLY HY1IPH 



STONEFLY NYMPH 



DAMSELFLY BYMFH 



o 
w 






UID6E LARVA 




CADDIS WORM 



&a 



c 



EXERCISE 34 

RECORDOF EXPERIMENTSON TRIAL AND ERROR 



FIRST CHICKEN 



Trial 


Spells of 
peeping 


Walks with 
change of 
direction 


Peerings 
through 

walls 


Flights 


Returns from 


Time 


1 


2 


3 


1 


















2 


















3 


















4 


















5 


















6 


















7 


















8 


















9 


















10 


















SECOND CHICKEN 


1 


















2 


















3 


















4 


















5 


















6 


















7 


















8 


















9 


















10 


















THIRD CHICKEN 


1 


















2 


















3 


















4 


















5 


















6 


















7 


















8 


















9 


















10 



















